diff --git a/src/Form/Service/Condition/BookingModeCondition.php b/src/Form/Service/Condition/BookingModeCondition.php
new file mode 100644
index 0000000..1df1671
--- /dev/null
+++ b/src/Form/Service/Condition/BookingModeCondition.php
@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Form\Service\Condition;
+
+use App\Form\Model\BookingDto;
+use App\Form\Service\Contract\FieldConditionInterface;
+
+/**
+ * Condition that evaluates based on the booking workflow mode.
+ *
+ * Used to apply field states that should only be active in a specific mode
+ * (create or edit), such as making room assignments readonly in edit mode.
+ */
+class BookingModeCondition implements FieldConditionInterface
+{
+    /**
+     * @param string $mode The mode to check against (BookingDto::MODE_CREATE or BookingDto::MODE_EDIT)
+     */
+    public function __construct(
+        private readonly string $mode,
+    ) {
+        if (BookingDto::MODE_CREATE !== $mode && BookingDto::MODE_EDIT !== $mode) {
+            throw new \InvalidArgumentException(sprintf('Invalid mode "%s". Must be one of: %s, %s', $mode, BookingDto::MODE_CREATE, BookingDto::MODE_EDIT));
+        }
+    }
+
+    public function evaluate(BookingDto $bookingDto, int $participantIndex, array $formData): bool
+    {
+        return $this->mode === $bookingDto->getMode();
+    }
+
+    public function getDependentFields(): array
+    {
+        return [];
+    }
+
+    public function getDescription(): string
+    {
+        return sprintf('Returns true when booking is in %s mode', $this->mode);
+    }
+}
diff --git a/src/Form/Service/CreateFieldStateProvider.php b/src/Form/Service/CreateFieldStateProvider.php
index 82c4837..5f406e0 100644
--- a/src/Form/Service/CreateFieldStateProvider.php
+++ b/src/Form/Service/CreateFieldStateProvider.php
@@ -263,8 +263,11 @@ class CreateFieldStateProvider extends AbstractFieldStateProvider
             'required' => new ApplicantCondition(),
         ];
 
-        // Render assignedRoomId field as static text when only one room type is selected (auto-assigned by RoomAssignmentService)
+        // Room assignment field:
+        // - Hidden until date of birth is provided (age determines room eligibility, e.g., Baby rooms)
+        // - Rendered as static text when only one room type is selected (auto-assigned by RoomAssignmentService)
         $this->fieldStateConditions['assignedRoomId'] = [
+            'hidden' => CompositeCondition::not($dateOfBirthProvidedCondition),
             'static_text' => new SingleRoomTypeCondition(),
         ];
 
diff --git a/src/Form/Service/EditFieldStateProvider.php b/src/Form/Service/EditFieldStateProvider.php
index 27aae15..23ba391 100644
--- a/src/Form/Service/EditFieldStateProvider.php
+++ b/src/Form/Service/EditFieldStateProvider.php
@@ -5,10 +5,12 @@ declare(strict_types=1);
 namespace App\Form\Service;
 
 use App\BusProNet\Utility\DirectionMapper;
+use App\Form\Model\BookingDto;
 use App\Form\Service\Abstract\AbstractFieldStateProvider;
 use App\Form\Service\Condition\AdditionalServicesMutabilityCondition;
 use App\Form\Service\Condition\ApplicantCondition;
 use App\Form\Service\Condition\AuthenticatedUserPersonalDataCondition;
+use App\Form\Service\Condition\BookingModeCondition;
 use App\Form\Service\Condition\CompositeCondition;
 use App\Form\Service\Condition\DateOfBirthProvidedCondition;
 use App\Form\Service\Condition\FieldValueCondition;
@@ -16,7 +18,6 @@ use App\Form\Service\Condition\PersonalDataMutabilityCondition;
 use App\Form\Service\Condition\PickupsMutabilityCondition;
 use App\Form\Service\Condition\RentalSelectionCondition;
 use App\Form\Service\Condition\ServiceSubTypeCondition;
-use App\Form\Service\Condition\SingleRoomTypeCondition;
 use App\Form\Service\Condition\SkiPassSelectionCondition;
 use App\Form\Service\Condition\TransportationServicesMutabilityCondition;
 
@@ -97,10 +98,10 @@ class EditFieldStateProvider extends AbstractFieldStateProvider
             'static_text' => $personalDataHiddenCondition,
         ];
 
-        // Render assignedRoomId field as static text when only one room type is selected (auto-assigned by RoomAssignmentService)
-        // Same logic as create mode - render as static text when only one room type available
+        // Room assignments are fixed in edit mode - always render as static text
+        // The assignedRoomId value passes through unchanged from the loaded booking data
         $this->fieldStateConditions['assignedRoomId'] = [
-            'static_text' => new SingleRoomTypeCondition(),
+            'static_text' => new BookingModeCondition(BookingDto::MODE_EDIT),
         ];
 
         // Conditional visibility for service fields (same as create flow)
diff --git a/templates/booking/_participant_form.html.twig b/templates/booking/_participant_form.html.twig
index a933582..6116f06 100644
--- a/templates/booking/_participant_form.html.twig
+++ b/templates/booking/_participant_form.html.twig
@@ -134,22 +134,24 @@
                 </div>
             {% endif %}
 
-            {# Room assignment #}
-            <div class="grid grid-cols-2 gap-4">
-                {% set assignedRoom = bookingDto.travel.getRoomById(form.vars.data.participant.assignedRoomId) %}
-                {% set roomLabel = assignedRoom ? assignedRoom.label : 'Kein Zimmer zugewiesen' %}
-                {{ macros.field_or_static(form, 'assignedRoomId', 'Zimmer', roomLabel, bookingDto, participantIndex, {
-                    'attr': {
-                        'hx-trigger': 'change',
-                        'hx-post': path(refreshRouteName, refreshRouteParams|default({index: participantIndex})),
-                        'hx-target': '#main-content',
-                        'hx-swap': 'innerHTML'
-                    }
-                }) }}
-                {% if form.remarksRoom is defined %}
-                    {{ form_row(form.remarksRoom) }}
-                {% endif %}
-            </div>
+            {# Room assignment - hidden until date of birth is provided, or shown as static text in edit mode #}
+            {% if form.assignedRoomId is defined or is_static_text('assignedRoomId', bookingDto, participantIndex) %}
+                <div class="grid grid-cols-2 gap-4">
+                    {% set assignedRoom = bookingDto.travel.getRoomById(form.vars.data.participant.assignedRoomId) %}
+                    {% set roomLabel = assignedRoom ? assignedRoom.label : 'Kein Zimmer zugewiesen' %}
+                    {{ macros.field_or_static(form, 'assignedRoomId', 'Zimmer', roomLabel, bookingDto, participantIndex, {
+                        'attr': {
+                            'hx-trigger': 'change',
+                            'hx-post': path(refreshRouteName, refreshRouteParams|default({index: participantIndex})),
+                            'hx-target': '#main-content',
+                            'hx-swap': 'innerHTML'
+                        }
+                    }) }}
+                    {% if form.remarksRoom is defined %}
+                        {{ form_row(form.remarksRoom) }}
+                    {% endif %}
+                </div>
+            {% endif %}
 
             {# Eligibility checks #}
             {% set participantData = form.vars.data.participant %}