diff --git a/Assets/BetterPhysics/Runtime/Scripts/BetterRigidbody.cs b/Assets/BetterPhysics/Runtime/Scripts/BetterRigidbody.cs
index 46fd663..39e0eba 100644
--- a/Assets/BetterPhysics/Runtime/Scripts/BetterRigidbody.cs
+++ b/Assets/BetterPhysics/Runtime/Scripts/BetterRigidbody.cs
@@ -226,7 +226,11 @@ private void ApplyHardLimit(SpeedLimit limit) {
             }
         }
 
+#if UNITY_6000_4_OR_NEWER
+        internal EntityId GetRigidbodyEntityId() => _rb.GetEntityId();
+#else
         internal int GetRigidbodyInstanceID() => _rb.GetInstanceID();
+#endif
         internal Rigidbody WrappedRigidbody => GetComponent<Rigidbody>();
 
         public Vector3 Velocity {
@@ -489,7 +493,9 @@ public void AddRelativeTorque(float x, float y, float z, ForceMode mode = ForceM
         public Action<Quaternion> MoveRotation => _rb.MoveRotation;
         public Action ResetCenterOfMass => _rb.ResetCenterOfMass;
         public Action ResetInertiaTensor => _rb.ResetInertiaTensor;
+#if !UNITY_6000_0_OR_NEWER
         public Action<float> SetDensity => _rb.SetDensity;
+#endif
         public Action Sleep => _rb.Sleep;
 
         public bool SweepTest(Vector3 direction, out RaycastHit hitInfo, float maxDistance = Mathf.Infinity,
@@ -838,4 +844,4 @@ private Vector3 CalculateVelocityChangeWithSoftLimit(in Vector3 currentVelocity,
 
         #endregion
     }
-}
\ No newline at end of file
+}
diff --git a/Assets/BetterPhysics/Runtime/Scripts/ContactModificationManager.cs b/Assets/BetterPhysics/Runtime/Scripts/ContactModificationManager.cs
index 4e8870d..0927828 100644
--- a/Assets/BetterPhysics/Runtime/Scripts/ContactModificationManager.cs
+++ b/Assets/BetterPhysics/Runtime/Scripts/ContactModificationManager.cs
@@ -29,10 +29,18 @@ public static ContactModificationManager Instance {
         /// </summary>
         public static ContactModificationManager WeakInstance => _instance;
 
+#if UNITY_6000_4_OR_NEWER
+        private Dictionary<EntityId, IDictionary<int, OneWayLayerInteraction>> _perRigidbodyData;
+#else
         private Dictionary<int, IDictionary<int, OneWayLayerInteraction>> _perRigidbodyData;
-        
+#endif
+
         // Tracks which BetterRigidbody is in which layer
+#if UNITY_6000_4_OR_NEWER
+        private Dictionary<EntityId, int> _rigidbodyLayerMapping;
+#else
         private Dictionary<int, int> _rigidbodyLayerMapping;
+#endif
         
         private BetterPhysicsSettings _settings;
 
@@ -54,8 +62,13 @@ private void PhysicsOnContactModifyEvent(PhysicsScene scene, NativeArray<Modifia
             for (int i = 0; i < contactPairs.Length; i++) {
                 var pair = contactPairs[i];
                 
+#if UNITY_6000_4_OR_NEWER
+                EntityId bodyAId = pair.bodyEntityId;
+                EntityId bodyBId = pair.otherBodyEntityId;
+#else
                 int bodyAId = pair.bodyInstanceID;
                 int bodyBId = pair.otherBodyInstanceID;
+#endif
                 
                 if (!_rigidbodyLayerMapping.TryGetValue(bodyAId, out int layerA)) {
                     // Debug.Log($"Body A {bodyAId} is not a registered BRB");
@@ -138,7 +151,11 @@ private void PhysicsOnContactModifyEvent(PhysicsScene scene, NativeArray<Modifia
         }
 
         public void Register(BetterRigidbody body) {
+#if UNITY_6000_4_OR_NEWER
+            var rbInstanceId = body.GetEntityId();
+#else
             var rbInstanceId = body.GetRigidbodyInstanceID();
+#endif
             _rigidbodyLayerMapping[rbInstanceId] = body.PhysicsLayer;
             _perRigidbodyData[rbInstanceId] = body.SerializedInteractions;
             
@@ -146,27 +163,43 @@ public void Register(BetterRigidbody body) {
         }
 
         public void UnRegister(BetterRigidbody body) {
+#if UNITY_6000_4_OR_NEWER
+            var rbInstanceId = body.GetEntityId();
+#else
             var rbInstanceId = body.GetRigidbodyInstanceID();
+#endif
             _perRigidbodyData.Remove(rbInstanceId);
             _rigidbodyLayerMapping.Remove(rbInstanceId);
         }
 
         public void ResetCustomInteractions(BetterRigidbody body) {
+#if UNITY_6000_4_OR_NEWER
+            var rbInstanceId = body.GetEntityId();
+#else
             var rbInstanceId = body.GetRigidbodyInstanceID();
+#endif
             if (_perRigidbodyData.TryGetValue(rbInstanceId, out var data)) {
                 data.Clear();
             }
         }
 
         public void SetCustomInteraction(BetterRigidbody body, OneWayLayerInteraction interaction) {
+#if UNITY_6000_4_OR_NEWER
+            var rbInstanceId = body.GetEntityId();
+#else
             var rbInstanceId = body.GetRigidbodyInstanceID();
+#endif
             if (_perRigidbodyData.TryGetValue(rbInstanceId, out var data)) {
                 data[interaction.receiver] = interaction;
             }
         }
 
         public bool RemoveCustomInteraction(BetterRigidbody body, int receiverLayer) {
+#if UNITY_6000_4_OR_NEWER
+            var rbInstanceId = body.GetEntityId();
+#else
             var rbInstanceId = body.GetRigidbodyInstanceID();
+#endif
             if (_perRigidbodyData.TryGetValue(rbInstanceId, out var data)) {
                 return data.Remove(receiverLayer);
             }
@@ -175,7 +208,11 @@ public bool RemoveCustomInteraction(BetterRigidbody body, int receiverLayer) {
         }
 
         public bool TryGetCustomInteraction(BetterRigidbody body, int receiverLayer, out OneWayLayerInteraction interaction) {
+#if UNITY_6000_4_OR_NEWER
+            var rbInstanceId = body.GetEntityId();
+#else
             var rbInstanceId = body.GetRigidbodyInstanceID();
+#endif
             if (_perRigidbodyData.TryGetValue(rbInstanceId, out var data)) {
                 return data.TryGetValue(receiverLayer, out interaction);
             }
@@ -185,9 +222,13 @@ public bool TryGetCustomInteraction(BetterRigidbody body, int receiverLayer, out
         }
 
         public void UpdateBodyLayer(BetterRigidbody body) {
+#if UNITY_6000_4_OR_NEWER
+            var rbInstanceId = body.GetEntityId();
+#else
             var rbInstanceId = body.GetRigidbodyInstanceID();
+#endif
             _rigidbodyLayerMapping.Remove(rbInstanceId);
             _rigidbodyLayerMapping[rbInstanceId] = body.PhysicsLayer;
         }
     }
-}
\ No newline at end of file
+}