diff --git a/mart/attack/composer.py b/mart/attack/composer.py
index ddfdc45b..7661b9f3 100644
--- a/mart/attack/composer.py
+++ b/mart/attack/composer.py
@@ -11,28 +11,14 @@
 
 import torch
 
+__all__ = ["Composer"]
 
-class Composer(abc.ABC):
-    def __call__(
-        self,
-        perturbation: torch.Tensor | tuple,
-        *,
-        input: torch.Tensor | tuple,
-        target: torch.Tensor | dict[str, Any] | tuple,
-        **kwargs,
-    ) -> torch.Tensor | tuple:
-        if isinstance(perturbation, tuple):
-            input_adv = tuple(
-                self.compose(perturbation_i, input=input_i, target=target_i)
-                for perturbation_i, input_i, target_i in zip(perturbation, input, target)
-            )
-        else:
-            input_adv = self.compose(perturbation, input=input, target=target)
 
-        return input_adv
+class Method(abc.ABC):
+    """Composition method base class."""
 
     @abc.abstractmethod
-    def compose(
+    def __call__(
         self,
         perturbation: torch.Tensor,
         *,
@@ -42,17 +28,17 @@ def compose(
         raise NotImplementedError
 
 
-class Additive(Composer):
+class Additive(Method):
     """We assume an adversary adds perturbation to the input."""
 
-    def compose(self, perturbation, *, input, target):
+    def __call__(self, perturbation, *, input, target):
         return input + perturbation
 
 
-class Overlay(Composer):
+class Overlay(Method):
     """We assume an adversary overlays a patch to the input."""
 
-    def compose(self, perturbation, *, input, target):
+    def __call__(self, perturbation, *, input, target):
         # True is mutable, False is immutable.
         mask = target["perturbable_mask"]
 
@@ -61,3 +47,52 @@ def compose(self, perturbation, *, input, target):
         mask = mask.to(input)
 
         return input * (1 - mask) + perturbation * mask
+
+
+class Composer:
+    """A modality-aware composer.
+
+    Example usage: `Composer(rgb=Overlay(), depth=Additive())`. Non-modality composer can be
+    defined as `Composer(method=Additive())`.
+    """
+
+    def __init__(self, **modality_methods):
+        self.modality_methods = modality_methods
+
+    def __call__(
+        self,
+        perturbation: torch.Tensor | dict[str, torch.Tensor] | tuple | list,
+        *,
+        input: torch.Tensor | dict[str, torch.Tensor] | tuple | list,
+        target: torch.Tensor | dict[str, Any] | tuple | list,
+        modality: str = "method",
+    ) -> torch.Tensor:
+        """Recursively compose output from perturbation and input."""
+        assert type(perturbation) == type(input)
+
+        if isinstance(perturbation, torch.Tensor):
+            # Finally we can compose output with tensors.
+            method = self.modality_methods[modality]
+            output = method(perturbation, input=input, target=target)
+            return output
+        elif isinstance(perturbation, dict):
+            # The dict input has modalities specified in keys, passing them recursively.
+            # For non-modality input that does not have dict, modality="method" by default.
+            output = {}
+            for modality in perturbation.keys():
+                output[modality] = self(
+                    perturbation[modality], input=input[modality], target=target, modality=modality
+                )
+            return output
+        elif isinstance(perturbation, (list, tuple)):
+            # We assume a modality-dictionary only contains tensors, but not list/tuple.
+            assert modality == "method"
+            # The list or tuple input is a collection of sub-input and sub-target.
+            output = []
+            for pert_i, input_i, target_i in zip(perturbation, input, target):
+                output.append(self(pert_i, input=input_i, target=target_i, modality=modality))
+            if isinstance(perturbation, tuple):
+                output = tuple(output)
+            return output
+        else:
+            raise ValueError(f"Unsupported data type of perturbation: {type(perturbation)}.")
diff --git a/mart/configs/attack/composer/additive.yaml b/mart/configs/attack/composer/additive.yaml
index c12f939e..ce31089a 100644
--- a/mart/configs/attack/composer/additive.yaml
+++ b/mart/configs/attack/composer/additive.yaml
@@ -1 +1,3 @@
-_target_: mart.attack.composer.Additive
+_target_: mart.attack.Composer
+method:
+  _target_: mart.attack.composer.Additive
diff --git a/mart/configs/attack/composer/overlay.yaml b/mart/configs/attack/composer/overlay.yaml
index 469f7245..fceaafc2 100644
--- a/mart/configs/attack/composer/overlay.yaml
+++ b/mart/configs/attack/composer/overlay.yaml
@@ -1 +1,3 @@
-_target_: mart.attack.composer.Overlay
+_target_: mart.attack.Composer
+method:
+  _target_: mart.attack.composer.Overlay
diff --git a/mart/configs/attack/composer/rgb_overlay_depth_additive.yaml b/mart/configs/attack/composer/rgb_overlay_depth_additive.yaml
new file mode 100644
index 00000000..50a182a9
--- /dev/null
+++ b/mart/configs/attack/composer/rgb_overlay_depth_additive.yaml
@@ -0,0 +1,5 @@
+_target_: mart.attack.Composer
+rgb:
+  _target_: mart.attack.composer.Overlay
+depth:
+  _target_: mart.attack.composer.Additive
diff --git a/mart/configs/attack/object_detection_rgb_mask_adversary.yaml b/mart/configs/attack/object_detection_rgb_mask_adversary.yaml
index a2bb039e..ba281992 100644
--- a/mart/configs/attack/object_detection_rgb_mask_adversary.yaml
+++ b/mart/configs/attack/object_detection_rgb_mask_adversary.yaml
@@ -7,7 +7,7 @@ defaults:
   - callbacks: [progress_bar, image_visualizer]
   - objective: zero_ap
   - gain: rcnn_training_loss
-  - composer: overlay
+  - composer: rgb_overlay_depth_additive
   - enforcer: default
   - enforcer/constraints@enforcer.rgb: [mask, pixel_range]
 
diff --git a/tests/test_composer.py b/tests/test_composer.py
index 06f215e6..315726d9 100644
--- a/tests/test_composer.py
+++ b/tests/test_composer.py
@@ -6,22 +6,87 @@
 
 import torch
 
-from mart.attack.composer import Additive, Overlay
+from mart.attack.composer import Additive, Composer, Overlay
 
 
-def test_additive_composer_forward(input_data, target_data, perturbation):
-    composer = Additive()
+def test_additive_method_forward(input_data, target_data, perturbation):
+    method = Additive()
 
-    output = composer(perturbation, input=input_data, target=target_data)
+    output = method(perturbation, input=input_data, target=target_data)
     expected_output = input_data + perturbation
     torch.testing.assert_close(output, expected_output, equal_nan=True)
 
 
-def test_overlay_composer_forward(input_data, target_data, perturbation):
-    composer = Overlay()
+def test_overlay_method_forward(input_data, target_data, perturbation):
+    method = Overlay()
 
-    output = composer(perturbation, input=input_data, target=target_data)
+    output = method(perturbation, input=input_data, target=target_data)
     mask = target_data["perturbable_mask"]
     mask = mask.to(input_data)
     expected_output = input_data * (1 - mask) + perturbation
     torch.testing.assert_close(output, expected_output, equal_nan=True)
+
+
+def test_non_modality_composer_forward(input_data, target_data, perturbation):
+    composer = Composer(method=Additive())
+
+    # tensor input
+    pert = perturbation
+    input = input_data
+    target = target_data
+    output = composer(pert, input=input, target=target)
+    expected_output = input_data + perturbation
+    torch.testing.assert_close(output, expected_output, equal_nan=True)
+
+    # tuple of tensor input
+    pert = (perturbation,)
+    input = (input_data,)
+    target = (target_data,)
+    output = composer(pert, input=input, target=target)
+    expected_output = (input_data + perturbation,)
+    assert type(output) == type(expected_output)
+    torch.testing.assert_close(output[0], expected_output[0], equal_nan=True)
+
+
+def test_modality_composer_forward(input_data, target_data, perturbation):
+    input = {"rgb": input_data, "depth": input_data}
+    target = target_data
+    pert = {"rgb": perturbation, "depth": perturbation}
+
+    rgb_method = Additive()
+    depth_method = Overlay()
+    composer = Composer(rgb=rgb_method, depth=depth_method)
+
+    # dict
+    output = composer(pert, input=input, target=target)
+    expected_output = {
+        "rgb": rgb_method(perturbation, input=input_data, target=target_data),
+        "depth": depth_method(perturbation, input=input_data, target=target_data),
+    }
+    assert type(output) == type(expected_output)
+    torch.testing.assert_close(output["rgb"], expected_output["rgb"], equal_nan=True)
+    torch.testing.assert_close(output["depth"], expected_output["depth"], equal_nan=True)
+
+    # list of dict
+    output = composer([pert], input=[input], target=[target])
+    expected_output = [
+        {
+            "rgb": rgb_method(perturbation, input=input_data, target=target_data),
+            "depth": depth_method(perturbation, input=input_data, target=target_data),
+        }
+    ]
+    assert type(output) == type(expected_output)
+    torch.testing.assert_close(output[0]["rgb"], expected_output[0]["rgb"], equal_nan=True)
+    torch.testing.assert_close(output[0]["depth"], expected_output[0]["depth"], equal_nan=True)
+
+    # tuple of dict
+    output = composer((pert,), input=(input,), target=(target,))
+    expected_output = (
+        {
+            "rgb": rgb_method(perturbation, input=input_data, target=target_data),
+            "depth": depth_method(perturbation, input=input_data, target=target_data),
+        },
+    )
+    assert type(output) == type(expected_output)
+    torch.testing.assert_close(output[0]["rgb"], expected_output[0]["rgb"], equal_nan=True)
+    torch.testing.assert_close(output[0]["depth"], expected_output[0]["depth"], equal_nan=True)