diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index a3d68b03..80ae9a9d 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -680,10 +680,29 @@ class ListSerializer(BaseSerializer):
                 api_settings.NON_FIELD_ERRORS_KEY: [message]
             }, code='min_length')
 
+        # Validate that instance length matches data length when instance is provided
+        if self.instance is not None and not isinstance(self.instance, models.manager.BaseManager):
+            if len(self.instance) != len(data):
+                raise AssertionError(
+                    'Mismatched instances and data items (%s instances for %s data items)' % 
+                    (len(self.instance), len(data))
+                )
+
         ret = []
         errors = []
 
-        for item in data:
+        for idx, item in enumerate(data):
+            # Set the instance on the child serializer to the corresponding item
+            # when validating in the context of many=True
+            if self.instance is not None and isinstance(self.instance, (list, tuple)):
+                child_instance = self.instance[idx]
+            else:
+                child_instance = getattr(self, 'instance', None)
+            
+            # Temporarily bind the child instance
+            old_child_instance = self.child.instance
+            self.child.instance = child_instance
+            
             try:
                 validated = self.child.run_validation(item)
             except ValidationError as exc:
@@ -691,6 +710,9 @@ class ListSerializer(BaseSerializer):
             else:
                 ret.append(validated)
                 errors.append({})
+            finally:
+                # Restore the original instance
+                self.child.instance = old_child_instance
 
         if any(errors):
             raise ValidationError(errors)