diff --git a/documentation/w3c_test_improvement_plan.md b/documentation/w3c_test_improvement_plan.md
new file mode 100644
index 0000000..62e8f3b
--- /dev/null
+++ b/documentation/w3c_test_improvement_plan.md
@@ -0,0 +1,158 @@
+# W3C Test Improvement Plan
+
+## Current Status
+
+**Test Pass Rate:** 22/59 W3C tests passing (37.3%)  
+**Recent Improvement:** Fixed multi-state initial configuration parsing - test576 and test413 now pass  
+**Baseline:** Up from 20/59 (34%) before the multi-state initial fix
+
+## High-Impact Quick Wins (Estimated 2-4 weeks)
+
+### 1. Enhanced Data Model Support
+
+**Impact:** ~8-12 additional tests  
+**Effort:** Medium
+
+- **Missing Features:**
+  - `<datamodel>` / `<data>` element initialization
+  - Enhanced variable storage and access patterns
+  - JavaScript-style expression evaluation improvements
+
+**Target Tests:** test277, test276sub1, test550, test551 (data manipulation tests)
+
+### 2. Improved Event Processing  
+
+**Impact:** ~6-8 additional tests  
+**Effort:** Medium
+
+- **Missing Features:**
+  - Enhanced event queuing semantics
+  - Proper event data handling and propagation
+  - Cross-state event communication improvements
+
+**Target Tests:** test399, test401, test402 (event processing tests)
+
+### 3. Advanced State Machine Features
+
+**Impact:** ~4-6 additional tests  
+**Effort:** Medium-High
+
+- **Missing Features:**
+  - Targetless transitions (internal transitions)
+  - Enhanced transition conflict resolution
+  - Improved parallel state semantics
+
+**Target Tests:** test406, test412, test416, test419, test423 (transition selection tests)
+
+## Medium-Term Improvements (4-8 weeks)
+
+### 4. Complete Executable Content
+
+**Impact:** ~8-10 additional tests  
+**Effort:** High
+
+- **Missing Features:**
+  - `<send>` elements with delay support
+  - `<script>` element execution
+  - Advanced `<foreach>` iteration constructs
+
+**Target Tests:** test155, test156, test525 (foreach tests), various send/script tests
+
+### 5. Advanced History State Features
+
+**Impact:** ~3-4 additional tests  
+**Effort:** Medium
+
+- **Missing Features:**
+  - Complex history restoration scenarios
+  - History state default transition improvements
+  - Deep vs shallow history edge cases
+
+**Target Tests:** test388, test579, test580 (advanced history tests)
+
+### 6. Final State Handling
+
+**Impact:** ~2-3 additional tests  
+**Effort:** Low-Medium
+
+- **Missing Features:**
+  - Enhanced final state semantics
+  - Proper final state event generation
+  - Final state hierarchy handling
+
+**Target Tests:** test570 (final state tests)
+
+## Implementation Strategy
+
+### Phase 1: Data Model Enhancement (Priority 1)
+
+1. **Parser Updates:** Enhance `<data>` element parsing with expression evaluation
+2. **Runtime Storage:** Improve datamodel variable storage and initialization
+3. **Expression Engine:** Integrate enhanced JavaScript-style expression evaluation
+4. **Test Integration:** Update test infrastructure to handle data-driven scenarios
+
+### Phase 2: Event Processing Improvements (Priority 2)  
+
+1. **Event Queue Semantics:** Implement proper internal/external event queuing per SCXML spec
+2. **Event Data Propagation:** Ensure event data is properly passed and accessible
+3. **Cross-State Communication:** Improve event handling between parallel regions
+4. **Validation Updates:** Enhance event-related validation rules
+
+### Phase 3: Advanced State Machine Features (Priority 3)
+
+1. **Targetless Transitions:** Implement internal transitions without target states  
+2. **Transition Conflict Resolution:** Enhance SCXML-compliant transition selection
+3. **Parallel State Semantics:** Improve concurrent execution and exit handling
+4. **Optimization:** Maintain O(1) lookup performance for advanced features
+
+## Success Metrics
+
+- **Phase 1 Target:** 30+ tests passing (51% pass rate)
+- **Phase 2 Target:** 36+ tests passing (61% pass rate)
+- **Phase 3 Target:** 42+ tests passing (71% pass rate)
+- **Ultimate Goal:** 50+ tests passing (85% pass rate)
+
+## Technical Approach
+
+### Maintain Architecture Principles
+
+- **Parse → Validate → Optimize** workflow
+- **O(1) lookup optimizations** for performance
+- **Comprehensive test coverage** for regressions
+- **SCXML specification compliance** over custom extensions
+
+### Development Workflow
+
+1. **Analyze failing tests** to identify specific missing features
+2. **Implement core functionality** with proper validation
+3. **Update test expectations** and fix any regressions
+4. **Run full test suite** to ensure no breaking changes
+5. **Measure improvement** against W3C test pass rate
+
+## Current Blockers Analysis
+
+### Most Common Test Failure Patterns
+
+1. **Data model operations** - Missing variable initialization and manipulation
+2. **Event handling** - Incomplete event queuing and processing semantics  
+3. **Transition selection** - Advanced SCXML transition conflict resolution
+4. **Executable content** - Missing `<send>`, `<script>`, and `<foreach>` support
+
+### Technical Debt to Address
+
+- Some tests create invalid document structures (fixed in multi-state work)
+- Expression evaluation needs JavaScript compatibility improvements
+- Event queuing semantics need W3C SCXML compliance review
+
+## Next Steps
+
+1. **Start with data model enhancement** - highest impact, medium effort
+2. **Create feature branch** for data model work  
+3. **Implement `<data>` element initialization** with expression evaluation
+4. **Update failing data-related tests** (test277, test276sub1, etc.)
+5. **Measure improvement** and proceed to event processing phase
+
+---
+
+*Last Updated: 2025-09-07*  
+*Status: 22/59 tests passing (37.3%) - recent multi-state initial configuration fix complete*
diff --git a/lib/statifier/document.ex b/lib/statifier/document.ex
index 6210cf6..0b5c324 100644
--- a/lib/statifier/document.ex
+++ b/lib/statifier/document.ex
@@ -5,10 +5,10 @@ defmodule Statifier.Document do
 
   defstruct [
     :name,
-    :initial,
     :datamodel,
     :version,
     :xmlns,
+    initial: [],
     states: [],
     datamodel_elements: [],
     # Performance optimization: O(1) lookups
@@ -30,10 +30,10 @@ defmodule Statifier.Document do
 
   @type t :: %__MODULE__{
           name: String.t() | nil,
-          initial: String.t() | nil,
           datamodel: String.t() | nil,
           version: String.t() | nil,
           xmlns: String.t() | nil,
+          initial: [String.t()],
           states: [Statifier.State.t()],
           datamodel_elements: [Statifier.Data.t()],
           # Lookup maps for O(1) access
diff --git a/lib/statifier/interpreter.ex b/lib/statifier/interpreter.ex
index 7f38484..5beb947 100644
--- a/lib/statifier/interpreter.ex
+++ b/lib/statifier/interpreter.ex
@@ -240,6 +240,8 @@ defmodule Statifier.Interpreter do
     end
   end
 
+  defp get_initial_configuration(%Document{initial: [], states: []}), do: %Configuration{}
+
   defp get_initial_configuration(%Document{initial: nil, states: []}), do: %Configuration{}
 
   defp get_initial_configuration(
@@ -249,16 +251,21 @@ defmodule Statifier.Interpreter do
     Configuration.new(initial_states)
   end
 
-  defp get_initial_configuration(%Document{initial: initial_id} = document) do
-    case Document.find_state(document, initial_id) do
-      # Invalid initial state
-      nil ->
-        %Configuration{}
+  defp get_initial_configuration(%Document{initial: [], states: [first_state | _rest]} = document) do
+    initial_states = enter_state(first_state, document)
+    Configuration.new(initial_states)
+  end
 
-      state ->
-        initial_states = enter_state(state, document)
-        Configuration.new(initial_states)
-    end
+  defp get_initial_configuration(%Document{initial: initial_ids} = document)
+       when length(initial_ids) > 0 do
+    initial_states =
+      initial_ids
+      |> Enum.map(&Document.find_state(document, &1))
+      # Remove any invalid states
+      |> Enum.filter(&(&1 != nil))
+      |> Enum.flat_map(&enter_state(&1, document))
+
+    Configuration.new(initial_states)
   end
 
   defp enter_state(%State{} = state, %Document{} = document),
@@ -283,17 +290,14 @@ defmodule Statifier.Interpreter do
   end
 
   defp enter_state(
-         %State{type: :compound, states: child_states, initial: initial_id},
+         %State{type: :compound, states: child_states, initial: initial_ids},
          %StateChart{} = state_chart
        ) do
-    # Compound state - find and enter initial child (don't add compound state to active set)
-    initial_child = get_initial_child_state(initial_id, child_states)
+    # Compound state - find and enter initial children (don't add compound state to active set)
+    initial_children = get_initial_child_states(initial_ids, child_states)
 
-    case initial_child do
-      # No valid child - compound state with no children is not active
-      nil -> []
-      child -> enter_state(child, state_chart)
-    end
+    initial_children
+    |> Enum.flat_map(&enter_state(&1, state_chart))
   end
 
   defp enter_state(
@@ -330,8 +334,23 @@ defmodule Statifier.Interpreter do
     end
   end
 
-  # Get the initial child state for a compound state
-  defp get_initial_child_state(nil, child_states) do
+  # Get the initial child states for a compound state (handles multiple initial states)
+  defp get_initial_child_states([], child_states) do
+    # No initial attribute - check for <initial> element first or use first child
+    case get_initial_child_state_legacy([], child_states) do
+      nil -> []
+      child -> [child]
+    end
+  end
+
+  defp get_initial_child_states(initial_ids, child_states) when is_list(initial_ids) do
+    initial_ids
+    |> Enum.map(&find_child_by_id(child_states, &1))
+    |> Enum.filter(&(&1 != nil))
+  end
+
+  # Legacy function for backward compatibility (single child)
+  defp get_initial_child_state_legacy([], child_states) do
     # No initial attribute - check for <initial> element first
     case find_initial_element(child_states) do
       %State{type: :initial, transitions: [transition | _rest]} ->
@@ -357,12 +376,6 @@ defmodule Statifier.Interpreter do
     end
   end
 
-  defp get_initial_child_state(initial_id, child_states) when is_binary(initial_id) do
-    Enum.find(child_states, &(&1.id == initial_id))
-  end
-
-  defp get_initial_child_state(_initial_id, []), do: nil
-
   # Find the initial element among child states
   defp find_initial_element(child_states) do
     Enum.find(child_states, &(&1.type == :initial))
diff --git a/lib/statifier/parser/scxml/element_builder.ex b/lib/statifier/parser/scxml/element_builder.ex
index 39e2d2a..b2ef60f 100644
--- a/lib/statifier/parser/scxml/element_builder.ex
+++ b/lib/statifier/parser/scxml/element_builder.ex
@@ -41,7 +41,7 @@ defmodule Statifier.Parser.SCXML.ElementBuilder do
 
     %Statifier.Document{
       name: get_attr_value(attrs_map, "name"),
-      initial: get_attr_value(attrs_map, "initial"),
+      initial: parse_initial_attribute(get_attr_value(attrs_map, "initial")),
       datamodel: get_attr_value(attrs_map, "datamodel"),
       version: get_attr_value(attrs_map, "version"),
       xmlns: get_attr_value(attrs_map, "xmlns"),
@@ -73,7 +73,7 @@ defmodule Statifier.Parser.SCXML.ElementBuilder do
 
     %Statifier.State{
       id: get_attr_value(attrs_map, "id"),
-      initial: get_attr_value(attrs_map, "initial"),
+      initial: parse_initial_attribute(get_attr_value(attrs_map, "initial")),
       # Will be updated later based on children and structure
       type: :atomic,
       states: [],
@@ -100,7 +100,7 @@ defmodule Statifier.Parser.SCXML.ElementBuilder do
     %Statifier.State{
       id: get_attr_value(attrs_map, "id"),
       # Parallel states don't have initial attributes
-      initial: nil,
+      initial: [],
       # Set type directly during parsing
       type: :parallel,
       states: [],
@@ -128,7 +128,7 @@ defmodule Statifier.Parser.SCXML.ElementBuilder do
     %Statifier.State{
       id: get_attr_value(attrs_map, "id"),
       # Final states don't have initial attributes
-      initial: nil,
+      initial: [],
       # Set type directly during parsing
       type: :final,
       states: [],
@@ -155,7 +155,7 @@ defmodule Statifier.Parser.SCXML.ElementBuilder do
     %Statifier.State{
       # Initial states generate unique IDs since they don't have explicit IDs
       id: generate_initial_id(element_counts),
-      initial: nil,
+      initial: [],
       type: :initial,
       states: [],
       transitions: [],
@@ -196,7 +196,7 @@ defmodule Statifier.Parser.SCXML.ElementBuilder do
 
     %Statifier.State{
       id: get_attr_value(attrs_map, "id"),
-      initial: nil,
+      initial: [],
       type: :history,
       history_type: history_type,
       states: [],
@@ -516,4 +516,18 @@ defmodule Statifier.Parser.SCXML.ElementBuilder do
     initial_count = Map.get(element_counts, "initial", 1)
     "__initial_#{initial_count}__"
   end
+
+  # Parse the initial attribute which can be space-separated state IDs.
+  #
+  # Returns a list of state IDs. If the attribute is nil or empty, returns an empty list.
+  # If it contains space-separated values, splits them and returns the list.
+  defp parse_initial_attribute(nil), do: []
+  defp parse_initial_attribute(""), do: []
+
+  defp parse_initial_attribute(initial_string) when is_binary(initial_string) do
+    initial_string
+    |> String.split()
+    |> Enum.map(&String.trim/1)
+    |> Enum.reject(&(&1 == ""))
+  end
 end
diff --git a/lib/statifier/state.ex b/lib/statifier/state.ex
index eef949e..303337f 100644
--- a/lib/statifier/state.ex
+++ b/lib/statifier/state.ex
@@ -32,7 +32,7 @@ defmodule Statifier.State do
 
   @type t :: %__MODULE__{
           id: String.t(),
-          initial: String.t() | nil,
+          initial: [String.t()],
           type: state_type(),
           states: [Statifier.State.t()],
           transitions: [Statifier.Transition.t()],
diff --git a/lib/statifier/validator/initial_state_validator.ex b/lib/statifier/validator/initial_state_validator.ex
index 2e5d36d..de7db00 100644
--- a/lib/statifier/validator/initial_state_validator.ex
+++ b/lib/statifier/validator/initial_state_validator.ex
@@ -13,20 +13,29 @@ defmodule Statifier.Validator.InitialStateValidator do
   """
   @spec validate_initial_state(Statifier.Validator.validation_result(), Statifier.Document.t()) ::
           Statifier.Validator.validation_result()
-  def validate_initial_state(%Statifier.Validator{} = result, %Statifier.Document{initial: nil}) do
+  def validate_initial_state(%Statifier.Validator{} = result, %Statifier.Document{initial: []}) do
     # No initial state specified - this is valid, first state becomes initial
     result
   end
 
+  def validate_initial_state(%Statifier.Validator{} = result, %Statifier.Document{initial: nil}) do
+    # Backward compatibility: nil initial state
+    result
+  end
+
   def validate_initial_state(
         %Statifier.Validator{} = result,
-        %Statifier.Document{initial: initial} = document
-      ) do
-    if Utils.state_exists?(initial, document) do
-      result
-    else
-      Utils.add_error(result, "Initial state '#{initial}' does not exist")
-    end
+        %Statifier.Document{initial: initial_ids} = document
+      )
+      when is_list(initial_ids) do
+    # Validate each initial state ID
+    Enum.reduce(initial_ids, result, fn initial_id, acc ->
+      if Utils.state_exists?(initial_id, document) do
+        acc
+      else
+        Utils.add_error(acc, "Initial state '#{initial_id}' does not exist")
+      end
+    end)
   end
 
   @doc """
@@ -56,28 +65,38 @@ defmodule Statifier.Validator.InitialStateValidator do
           Statifier.Document.t()
         ) ::
           Statifier.Validator.validation_result()
+  def validate_initial_state_hierarchy(%Statifier.Validator{} = result, %Statifier.Document{
+        initial: []
+      }) do
+    result
+  end
+
   def validate_initial_state_hierarchy(%Statifier.Validator{} = result, %Statifier.Document{
         initial: nil
       }) do
+    # Backward compatibility: nil initial state
     result
   end
 
   def validate_initial_state_hierarchy(
         %Statifier.Validator{} = result,
-        %Statifier.Document{initial: initial_id} = document
-      ) do
-    # Check if initial state is a direct child of the document (top-level)
-    if Enum.any?(document.states, &(&1.id == initial_id)) do
-      result
-    else
-      Utils.add_warning(result, "Document initial state '#{initial_id}' is not a top-level state")
-    end
+        %Statifier.Document{initial: initial_ids} = document
+      )
+      when is_list(initial_ids) do
+    # Check if all initial states are direct children of the document (top-level)
+    Enum.reduce(initial_ids, result, fn initial_id, acc ->
+      if Enum.any?(document.states, &(&1.id == initial_id)) do
+        acc
+      else
+        Utils.add_warning(acc, "Document initial state '#{initial_id}' is not a top-level state")
+      end
+    end)
   end
 
   # Validate that compound states with initial attributes reference valid child states
   defp validate_compound_state_initial(
          %Statifier.Validator{} = result,
-         %Statifier.State{initial: nil} = state,
+         %Statifier.State{initial: []} = state,
          _document
        ) do
     # No initial attribute - check for initial element validation
@@ -86,14 +105,24 @@ defmodule Statifier.Validator.InitialStateValidator do
 
   defp validate_compound_state_initial(
          %Statifier.Validator{} = result,
-         %Statifier.State{initial: initial_id} = state,
+         %Statifier.State{initial: nil} = state,
          _document
        ) do
+    # Backward compatibility: nil initial state
+    validate_initial_element(result, state)
+  end
+
+  defp validate_compound_state_initial(
+         %Statifier.Validator{} = result,
+         %Statifier.State{initial: initial_ids} = state,
+         _document
+       )
+       when is_list(initial_ids) and length(initial_ids) > 0 do
     result
     # First check if state has both initial attribute and initial element (invalid)
     |> validate_no_conflicting_initial_specs(state)
-    # Then validate the initial attribute reference
-    |> validate_initial_attribute_reference(state, initial_id)
+    # Then validate each initial attribute reference
+    |> validate_initial_attribute_references(state, initial_ids)
   end
 
   # Validate that a state doesn't have both initial attribute and initial element
@@ -102,8 +131,9 @@ defmodule Statifier.Validator.InitialStateValidator do
          %Statifier.State{initial: initial_attr} = state
        ) do
     has_initial_element = Enum.any?(state.states, &(&1.type == :initial))
+    has_initial_attr = is_list(initial_attr) and length(initial_attr) > 0
 
-    if initial_attr && has_initial_element do
+    if has_initial_attr and has_initial_element do
       Utils.add_error(
         result,
         "State '#{state.id}' cannot have both initial attribute and initial element - use one or the other"
@@ -113,21 +143,24 @@ defmodule Statifier.Validator.InitialStateValidator do
     end
   end
 
-  # Validate the initial attribute reference
-  defp validate_initial_attribute_reference(
+  # Validate multiple initial attribute references
+  defp validate_initial_attribute_references(
          %Statifier.Validator{} = result,
          %Statifier.State{} = state,
-         initial_id
-       ) do
-    # Check if the initial state is a direct child of this compound state
-    if Enum.any?(state.states, &(&1.id == initial_id)) do
-      result
-    else
-      Utils.add_error(
-        result,
-        "State '#{state.id}' specifies initial='#{initial_id}' but '#{initial_id}' is not a direct child"
-      )
-    end
+         initial_ids
+       )
+       when is_list(initial_ids) do
+    # Check each initial state is a direct child of this compound state
+    Enum.reduce(initial_ids, result, fn initial_id, acc ->
+      if Enum.any?(state.states, &(&1.id == initial_id)) do
+        acc
+      else
+        Utils.add_error(
+          acc,
+          "State '#{state.id}' specifies initial='#{initial_id}' but '#{initial_id}' is not a direct child"
+        )
+      end
+    end)
   end
 
   # Validate initial element constraints
diff --git a/test/passing_tests.json b/test/passing_tests.json
index d400f76..26e75af 100644
--- a/test/passing_tests.json
+++ b/test/passing_tests.json
@@ -5,7 +5,7 @@
     "test/statifier/**/*_test.exs",
     "test/mix/**/*_test.exs"
   ],
-  "last_updated": "2025-09-02",
+  "last_updated": "2025-09-07",
   "scion_tests": [
     "test/scion_tests/actionSend/send1_test.exs",
     "test/scion_tests/actionSend/send2_test.exs",
@@ -93,6 +93,7 @@
     "test/scxml_tests/mandatory/SelectingTransitions/test403a_test.exs",
     "test/scxml_tests/mandatory/SelectingTransitions/test407_test.exs",
     "test/scxml_tests/mandatory/SelectingTransitions/test411_test.exs",
+    "test/scxml_tests/mandatory/SelectingTransitions/test413_test.exs",
     "test/scxml_tests/mandatory/SelectingTransitions/test419_test.exs",
     "test/scxml_tests/mandatory/SelectingTransitions/test503_test.exs",
     "test/scxml_tests/mandatory/data/test280_test.exs",
@@ -108,6 +109,7 @@
     "test/scxml_tests/mandatory/onexit/test377_test.exs",
     "test/scxml_tests/mandatory/onexit/test378_test.exs",
     "test/scxml_tests/mandatory/raise/test144_test.exs",
-    "test/scxml_tests/mandatory/scxml/test355_test.exs"
+    "test/scxml_tests/mandatory/scxml/test355_test.exs",
+    "test/scxml_tests/mandatory/scxml/test576_test.exs"
   ]
 }
\ No newline at end of file
diff --git a/test/statifier/actions/invoke_action_test.exs b/test/statifier/actions/invoke_action_test.exs
index 4af7d7f..2cfa76c 100644
--- a/test/statifier/actions/invoke_action_test.exs
+++ b/test/statifier/actions/invoke_action_test.exs
@@ -8,7 +8,7 @@ defmodule Statifier.Actions.InvokeActionTest do
   defp create_test_state_chart(datamodel \\ %{}, invoke_handlers \\ %{}) do
     document = %Statifier.Document{
       name: nil,
-      initial: "test",
+      initial: ["test"],
       states: [],
       state_lookup: %{},
       transitions_by_source: %{}
diff --git a/test/statifier/actions/send_action_test.exs b/test/statifier/actions/send_action_test.exs
index 750f9e7..8c0b3b3 100644
--- a/test/statifier/actions/send_action_test.exs
+++ b/test/statifier/actions/send_action_test.exs
@@ -8,7 +8,7 @@ defmodule Statifier.Actions.SendActionTest do
   defp create_test_state_chart(datamodel \\ %{}) do
     document = %Statifier.Document{
       name: nil,
-      initial: "test",
+      initial: ["test"],
       states: [],
       state_lookup: %{},
       transitions_by_source: %{}
diff --git a/test/statifier/history/history_resolution_test.exs b/test/statifier/history/history_resolution_test.exs
index 54ed9d2..bfef376 100644
--- a/test/statifier/history/history_resolution_test.exs
+++ b/test/statifier/history/history_resolution_test.exs
@@ -24,14 +24,14 @@ defmodule Statifier.HistoryResolutionTest do
             %State{
               id: "parent",
               type: :compound,
-              initial: "child1",
+              initial: ["child1"],
               states: [
                 %State{id: "child1", type: :atomic, parent: "parent"},
                 %State{id: "child2", type: :atomic, parent: "parent"},
                 %State{
                   id: "nested",
                   type: :compound,
-                  initial: "grandchild1",
+                  initial: ["grandchild1"],
                   parent: "parent",
                   states: [
                     %State{id: "grandchild1", type: :atomic, parent: "nested"},
diff --git a/test/statifier/history/interpreter_history_simple_test.exs b/test/statifier/history/interpreter_history_simple_test.exs
index 40715f1..4319d6e 100644
--- a/test/statifier/history/interpreter_history_simple_test.exs
+++ b/test/statifier/history/interpreter_history_simple_test.exs
@@ -12,7 +12,7 @@ defmodule Statifier.InterpreterHistorySimpleTest do
             %State{
               id: "parent",
               type: :compound,
-              initial: "child1",
+              initial: ["child1"],
               states: [
                 %State{id: "child1", type: :atomic, parent: "parent"},
                 %State{id: "child2", type: :atomic, parent: "parent"},
@@ -62,7 +62,7 @@ defmodule Statifier.InterpreterHistorySimpleTest do
             %State{
               id: "simple_parent",
               type: :compound,
-              initial: "child1",
+              initial: ["child1"],
               states: [
                 %State{id: "child1", type: :atomic, parent: "simple_parent"},
                 %State{id: "child2", type: :atomic, parent: "simple_parent"}
diff --git a/test/statifier/interpreter/logging_configuration_test.exs b/test/statifier/interpreter/logging_configuration_test.exs
index 1a5c19f..d37caf7 100644
--- a/test/statifier/interpreter/logging_configuration_test.exs
+++ b/test/statifier/interpreter/logging_configuration_test.exs
@@ -7,9 +7,9 @@ defmodule Statifier.Interpreter.LoggingConfigurationTest do
   # Simple test document for initialization tests
   @test_document %Document{
     name: "test",
-    initial: "idle",
+    initial: ["idle"],
     states: [
-      %Statifier.State{id: "idle", initial: nil, parent: nil, states: [], transitions: []}
+      %Statifier.State{id: "idle", initial: [], parent: nil, states: [], transitions: []}
     ],
     state_lookup: %{"idle" => %Statifier.State{id: "idle"}},
     transitions_by_source: %{},
diff --git a/test/statifier/interpreter_coverage_test.exs b/test/statifier/interpreter_coverage_test.exs
index c7700c2..00db8cf 100644
--- a/test/statifier/interpreter_coverage_test.exs
+++ b/test/statifier/interpreter_coverage_test.exs
@@ -7,7 +7,7 @@ defmodule Statifier.InterpreterCoverageTest do
       # Test initializing interpreter with empty document
       empty_document = %Document{
         states: [],
-        initial: nil,
+        initial: [],
         state_lookup: %{},
         transitions_by_source: %{}
       }
@@ -31,7 +31,7 @@ defmodule Statifier.InterpreterCoverageTest do
 
       document = %Document{
         states: [state1],
-        initial: "state1",
+        initial: ["state1"],
         state_lookup: %{"state1" => state1},
         transitions_by_source: %{"state1" => []}
       }
@@ -308,7 +308,7 @@ defmodule Statifier.InterpreterCoverageTest do
     test "initialize with validation error returns error tuple" do
       # Create an unvalidated document with validation errors
       unvalidated_document = %Document{
-        initial: "nonexistent",
+        initial: ["nonexistent"],
         states: [%State{id: "s1", type: :atomic, states: [], transitions: []}],
         validated: false,
         state_lookup: %{"s1" => %State{id: "s1", type: :atomic, states: [], transitions: []}},
@@ -324,7 +324,7 @@ defmodule Statifier.InterpreterCoverageTest do
     test "get_initial_configuration with invalid initial state" do
       # Test document with nonexistent initial state - covers the nil case in get_initial_configuration
       document = %Document{
-        initial: "nonexistent_state",
+        initial: ["nonexistent_state"],
         states: [%State{id: "s1", type: :atomic, states: [], transitions: []}],
         validated: true,
         state_lookup: %{"s1" => %State{id: "s1", type: :atomic, states: [], transitions: []}},
@@ -420,7 +420,7 @@ defmodule Statifier.InterpreterCoverageTest do
     test "compound state with no children" do
       # Test compound state with empty children list - covers the nil return case
       document = %Document{
-        initial: "empty_compound",
+        initial: ["empty_compound"],
         states: [
           %State{
             id: "empty_compound",
@@ -428,7 +428,7 @@ defmodule Statifier.InterpreterCoverageTest do
             # No children
             states: [],
             transitions: [],
-            initial: nil
+            initial: []
           }
         ],
         validated: true,
@@ -438,7 +438,7 @@ defmodule Statifier.InterpreterCoverageTest do
             type: :compound,
             states: [],
             transitions: [],
-            initial: nil
+            initial: []
           }
         },
         transitions_by_source: %{}
diff --git a/test/statifier/parser/scxml/final_state_test.exs b/test/statifier/parser/scxml/final_state_test.exs
index 9568c5f..55bd3ff 100644
--- a/test/statifier/parser/scxml/final_state_test.exs
+++ b/test/statifier/parser/scxml/final_state_test.exs
@@ -22,7 +22,7 @@ defmodule Statifier.Parser.SCXML.FinalStateTest do
     assert final_state != nil
     assert final_state.type == :final
     assert final_state.id == "final_state"
-    assert final_state.initial == nil
+    assert final_state.initial == []
     assert final_state.states == []
     assert final_state.transitions == []
   end
@@ -140,7 +140,7 @@ defmodule Statifier.Parser.SCXML.FinalStateTest do
     assert final_state != nil
     assert final_state.type == :final
     assert final_state.states == []
-    assert final_state.initial == nil
+    assert final_state.initial == []
     assert final_state.initial_location == nil
   end
 
diff --git a/test/statifier/parser/scxml_test.exs b/test/statifier/parser/scxml_test.exs
index 6edd651..67dbd28 100644
--- a/test/statifier/parser/scxml_test.exs
+++ b/test/statifier/parser/scxml_test.exs
@@ -16,12 +16,12 @@ defmodule Statifier.Parser.SCXMLTest do
               %Document{
                 xmlns: "http://www.w3.org/2005/07/scxml",
                 version: "1.0",
-                initial: "a",
+                initial: ["a"],
                 document_order: 1,
                 states: [
                   %Statifier.State{
                     id: "a",
-                    initial: nil,
+                    initial: [],
                     document_order: 2,
                     states: [],
                     transitions: []
@@ -103,7 +103,7 @@ defmodule Statifier.Parser.SCXMLTest do
                 states: [
                   %Statifier.State{
                     id: "parent",
-                    initial: "child1",
+                    initial: ["child1"],
                     states: [
                       %Statifier.State{
                         id: "child1",
@@ -133,10 +133,10 @@ defmodule Statifier.Parser.SCXMLTest do
 
       assert {:ok,
               %Document{
-                initial: nil,
+                initial: [],
                 states: [
                   %Statifier.State{
-                    initial: nil,
+                    initial: [],
                     transitions: [
                       %Statifier.Transition{
                         event: nil,
@@ -231,7 +231,7 @@ defmodule Statifier.Parser.SCXMLTest do
                 name: nil,
                 states: [
                   %Statifier.State{
-                    initial: nil,
+                    initial: [],
                     transitions: [
                       %Statifier.Transition{
                         event: nil,
diff --git a/test/statifier/state_chart_test.exs b/test/statifier/state_chart_test.exs
index 11ef702..17f051c 100644
--- a/test/statifier/state_chart_test.exs
+++ b/test/statifier/state_chart_test.exs
@@ -6,7 +6,7 @@ defmodule Statifier.StateChartTest do
   setup do
     document = %Document{
       name: "test_chart",
-      initial: "state_a",
+      initial: ["state_a"],
       states: []
     }
 
diff --git a/test/statifier/validator/edge_cases_test.exs b/test/statifier/validator/edge_cases_test.exs
index f947fc1..9a86ce3 100644
--- a/test/statifier/validator/edge_cases_test.exs
+++ b/test/statifier/validator/edge_cases_test.exs
@@ -65,7 +65,7 @@ defmodule Statifier.Validator.EdgeCasesTest do
     test "handles invalid initial state reference in compound state" do
       child1 = %State{id: "child1", states: []}
       child2 = %State{id: "child2", states: []}
-      parent = %State{id: "parent", initial: "nonexistent", states: [child1, child2]}
+      parent = %State{id: "parent", initial: ["nonexistent"], states: [child1, child2]}
       document = %Document{states: [parent]}
 
       {:error, errors, _warnings} = Validator.validate(document)
@@ -79,7 +79,7 @@ defmodule Statifier.Validator.EdgeCasesTest do
     test "handles unreachable state from first state when no initial specified" do
       state1 = %State{id: "first", transitions: [], states: []}
       state2 = %State{id: "unreachable", transitions: [], states: []}
-      document = %Document{initial: nil, states: [state1, state2]}
+      document = %Document{initial: [], states: [state1, state2]}
 
       {:ok, _document, warnings} = Validator.validate(document)
 
@@ -90,7 +90,7 @@ defmodule Statifier.Validator.EdgeCasesTest do
     test "handles document initial state that is not top-level" do
       child = %State{id: "nested_initial", states: []}
       parent = %State{id: "parent", states: [child]}
-      document = %Document{initial: "nested_initial", states: [parent]}
+      document = %Document{initial: ["nested_initial"], states: [parent]}
 
       {:ok, _document, warnings} = Validator.validate(document)
 
@@ -151,7 +151,7 @@ defmodule Statifier.Validator.EdgeCasesTest do
       child = %State{id: "child", states: [grandchild]}
       parent = %State{id: "parent", states: [child]}
       unreachable = %State{id: "unreachable", states: []}
-      document = %Document{initial: "parent", states: [parent, unreachable]}
+      document = %Document{initial: ["parent"], states: [parent, unreachable]}
 
       {:ok, _document, warnings} = Validator.validate(document)
 
@@ -165,7 +165,7 @@ defmodule Statifier.Validator.EdgeCasesTest do
       state1 = %State{id: "s1", transitions: [transition], states: []}
       state2 = %State{id: "s2", transitions: [], states: []}
       unreachable = %State{id: "unreachable", states: []}
-      document = %Document{initial: "s1", states: [state1, state2, unreachable]}
+      document = %Document{initial: ["s1"], states: [state1, state2, unreachable]}
 
       {:ok, _document, warnings} = Validator.validate(document)
 
@@ -179,7 +179,7 @@ defmodule Statifier.Validator.EdgeCasesTest do
       transition2 = %Transition{event: "back", targets: ["s1"]}
       state1 = %State{id: "s1", transitions: [transition1], states: []}
       state2 = %State{id: "s2", transitions: [transition2], states: []}
-      document = %Document{initial: "s1", states: [state1, state2]}
+      document = %Document{initial: ["s1"], states: [state1, state2]}
 
       {:ok, _document, warnings} = Validator.validate(document)
 
diff --git a/test/statifier/validator/history_state_validator_test.exs b/test/statifier/validator/history_state_validator_test.exs
index f92c3e6..fd48acc 100644
--- a/test/statifier/validator/history_state_validator_test.exs
+++ b/test/statifier/validator/history_state_validator_test.exs
@@ -74,7 +74,7 @@ defmodule Statifier.Validator.HistoryStateValidatorTest do
       document = %Document{
         version: "1.0",
         xmlns: "http://www.w3.org/2005/07/scxml",
-        initial: "main",
+        initial: ["main"],
         states: [
           %Statifier.State{
             id: "main",
@@ -183,7 +183,7 @@ defmodule Statifier.Validator.HistoryStateValidatorTest do
       document = %Document{
         version: "1.0",
         xmlns: "http://www.w3.org/2005/07/scxml",
-        initial: "main",
+        initial: ["main"],
         states: [
           %Statifier.State{
             id: "main",
@@ -227,7 +227,7 @@ defmodule Statifier.Validator.HistoryStateValidatorTest do
       document = %Document{
         version: "1.0",
         xmlns: "http://www.w3.org/2005/07/scxml",
-        initial: "main",
+        initial: ["main"],
         states: [
           %Statifier.State{
             id: "main",
@@ -286,7 +286,7 @@ defmodule Statifier.Validator.HistoryStateValidatorTest do
       document = %Document{
         version: "1.0",
         xmlns: "http://www.w3.org/2005/07/scxml",
-        initial: "main",
+        initial: ["main"],
         states: [
           %Statifier.State{
             id: "main",
@@ -327,12 +327,12 @@ defmodule Statifier.Validator.HistoryStateValidatorTest do
       document = %Document{
         version: "1.0",
         xmlns: "http://www.w3.org/2005/07/scxml",
-        initial: "main",
+        initial: ["main"],
         states: [
           %Statifier.State{
             id: "main",
             type: :compound,
-            initial: "sub1",
+            initial: ["sub1"],
             states: [
               %Statifier.State{
                 id: "hist",
@@ -382,7 +382,7 @@ defmodule Statifier.Validator.HistoryStateValidatorTest do
       document = %Document{
         version: "1.0",
         xmlns: "http://www.w3.org/2005/07/scxml",
-        initial: "main",
+        initial: ["main"],
         states: [
           %Statifier.State{
             id: "rootHist",
diff --git a/test/statifier_test.exs b/test/statifier_test.exs
index 3390623..5dd9edf 100644
--- a/test/statifier_test.exs
+++ b/test/statifier_test.exs
@@ -16,7 +16,7 @@ defmodule StatifierTest do
       assert {:ok, document, warnings} = Statifier.parse(xml)
       assert %Document{} = document
       assert document.name == nil
-      assert document.initial == "start"
+      assert document.initial == ["start"]
       assert document.validated == true
       assert is_list(warnings)
     end
@@ -68,7 +68,7 @@ defmodule StatifierTest do
 
       assert {:ok, document, warnings} = Statifier.parse(xml)
       assert document.validated == true
-      assert document.initial == "start"
+      assert document.initial == ["start"]
       assert document.xmlns == "http://www.w3.org/2005/07/scxml"
       assert document.version == "1.0"
       assert is_list(warnings)
@@ -84,7 +84,7 @@ defmodule StatifierTest do
 
       assert {:ok, document, _warnings} = Statifier.parse(xml)
       assert document.validated == true
-      assert document.initial == "start"
+      assert document.initial == ["start"]
       assert document.xmlns == "http://www.w3.org/2005/07/scxml"
       assert document.version == "1.0"
     end
@@ -98,7 +98,7 @@ defmodule StatifierTest do
 
       assert {:ok, document, _warnings} = Statifier.parse(xml)
       assert document.validated == true
-      assert document.initial == "start"
+      assert document.initial == ["start"]
       # XML declaration should not be added by default
     end
 
@@ -111,7 +111,7 @@ defmodule StatifierTest do
 
       assert {:ok, document, _warnings} = Statifier.parse(xml, xml_declaration: true)
       assert document.validated == true
-      assert document.initial == "start"
+      assert document.initial == ["start"]
     end
 
     test "returns validation errors when document is invalid" do
diff --git a/test/support/statifier_case.ex b/test/support/statifier_case.ex
index d6af6e2..6430864 100644
--- a/test/support/statifier_case.ex
+++ b/test/support/statifier_case.ex
@@ -136,7 +136,8 @@ defmodule Statifier.Case do
     }
 
     # Configure with default logging from environment
-    LogManager.configure_from_options(state_chart, [])
+    state_chart
+    |> LogManager.configure_from_options([])
   end
 
   @doc """