diff --git a/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py b/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py
index f3ee7b0f7..1e551bc39 100644
--- a/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py
+++ b/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py
@@ -419,7 +419,7 @@ class ConvolutionModule(nn.Module):
             assert cache.shape == (B, D, self.cache_size), cache.shape
         x = torch.cat([cache, x], dim=2)  # (B, D, cache_size + U + R)
         # update cache
-        new_cache = x[:, :, -R - self.cache_size:-R]
+        new_cache = x[:, :, -R - self.cache_size : -R]
 
         # 1-D depth-wise conv
         x = self.depthwise_conv(x)  # (B, D, U + R)
@@ -572,7 +572,7 @@ class EmformerAttention(nn.Module):
         Args:
           x: Input tensor, of shape (B, nhead, U, PE).
              U is the length of query vector.
-             For training mode, PE = 2 * U - 1;
+             For training and validation mode, PE = 2 * U - 1;
              for inference mode, PE = L + 2 * U - 1.
 
         Returns:
@@ -666,7 +666,7 @@ class EmformerAttention(nn.Module):
             L = left_context_key.size(0)
             assert PE == L + 2 * U - 1
         else:
-            # training mode
+            # training and validation mode
             assert PE == 2 * U - 1
         pos_emb = (
             self.linear_pos(pos_emb)
@@ -679,7 +679,7 @@ class EmformerAttention(nn.Module):
         )  # (B, nhead, U, PE)
         # rel-shift operation
         matrix_bd_utterance = self._rel_shift(matrix_bd_utterance)
-        # (B, nhead, U, U) for training mode;
+        # (B, nhead, U, U) for training and validation mode;
         # (B, nhead, U, L + U) for inference mode.
         matrix_bd_utterance = matrix_bd_utterance.contiguous().view(
             B * self.nhead, U, -1
@@ -730,7 +730,7 @@ class EmformerAttention(nn.Module):
         pos_emb: torch.Tensor,
     ) -> Tuple[torch.Tensor, torch.Tensor]:
         # TODO: Modify docs.
-        """Forward pass for training mode.
+        """Forward pass for training and validation mode.
 
         B: batch size;
         D: embedding dimension;
@@ -922,3 +922,464 @@ class EmformerAttention(nn.Module):
             key[M + R :],
             value[M + R :],
         )
+
+
+class EmformerEncoderLayer(nn.Module):
+    """Emformer layer that constitutes Emformer.
+
+    Args:
+      d_model (int):
+        Input dimension.
+      nhead (int):
+        Number of attention heads.
+      dim_feedforward (int):
+        Hidden layer dimension of feedforward network.
+      chunk_length (int):
+        Length of each input segment.
+      dropout (float, optional):
+        Dropout probability. (Default: 0.0)
+      layer_dropout (float, optional):
+        Layer dropout probability. (Default: 0.0)
+      cnn_module_kernel (int):
+        Kernel size of convolution module.
+      left_context_length (int, optional):
+        Length of left context. (Default: 0)
+      right_context_length (int, optional):
+        Length of right context. (Default: 0)
+      max_memory_size (int, optional):
+        Maximum number of memory elements to use. (Default: 0)
+      tanh_on_mem (bool, optional):
+        If ``True``, applies tanh to memory elements. (Default: ``False``)
+      negative_inf (float, optional):
+        Value to use for negative infinity in attention weights. (Default: -1e8)
+    """
+
+    def __init__(
+        self,
+        d_model: int,
+        nhead: int,
+        dim_feedforward: int,
+        chunk_length: int,
+        dropout: float = 0.1,
+        layer_dropout: float = 0.075,
+        cnn_module_kernel: int = 31,
+        left_context_length: int = 0,
+        right_context_length: int = 0,
+        max_memory_size: int = 0,
+        tanh_on_mem: bool = False,
+        negative_inf: float = -1e8,
+    ):
+        super().__init__()
+
+        self.attention = EmformerAttention(
+            embed_dim=d_model,
+            nhead=nhead,
+            dropout=dropout,
+            tanh_on_mem=tanh_on_mem,
+            negative_inf=negative_inf,
+        )
+        self.summary_op = nn.AvgPool1d(
+            kernel_size=chunk_length, stride=chunk_length, ceil_mode=True
+        )
+
+        self.feed_forward_macaron = nn.Sequential(
+            ScaledLinear(d_model, dim_feedforward),
+            ActivationBalancer(channel_dim=-1),
+            DoubleSwish(),
+            nn.Dropout(dropout),
+            ScaledLinear(dim_feedforward, d_model, initial_scale=0.25),
+        )
+
+        self.feed_forward = nn.Sequential(
+            ScaledLinear(d_model, dim_feedforward),
+            ActivationBalancer(channel_dim=-1),
+            DoubleSwish(),
+            nn.Dropout(dropout),
+            ScaledLinear(dim_feedforward, d_model, initial_scale=0.25),
+        )
+
+        self.conv_module = ConvolutionModule(
+            chunk_length,
+            right_context_length,
+            d_model,
+            cnn_module_kernel,
+        )
+
+        self.norm_final = BasicNorm(d_model)
+
+        # try to ensure the output is close to zero-mean
+        # (or at least, zero-median).
+        self.balancer = ActivationBalancer(
+            channel_dim=-1, min_positive=0.45, max_positive=0.55, max_abs=6.0
+        )
+
+        self.dropout = nn.Dropout(dropout)
+
+        self.layer_dropout = layer_dropout
+        self.left_context_length = left_context_length
+        self.chunk_length = chunk_length
+        self.max_memory_size = max_memory_size
+        self.d_model = d_model
+        self.use_memory = max_memory_size > 0
+
+    def _init_state(
+        self, batch_size: int, device: Optional[torch.device]
+    ) -> List[torch.Tensor]:
+        """Initialize states with zeros."""
+        empty_memory = torch.zeros(
+            self.max_memory_size, batch_size, self.d_model, device=device
+        )
+        left_context_key = torch.zeros(
+            self.left_context_length, batch_size, self.d_model, device=device
+        )
+        left_context_val = torch.zeros(
+            self.left_context_length, batch_size, self.d_model, device=device
+        )
+        past_length = torch.zeros(
+            1, batch_size, dtype=torch.int32, device=device
+        )
+        return [empty_memory, left_context_key, left_context_val, past_length]
+
+    def _unpack_state(
+        self, state: List[torch.Tensor]
+    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+        """Unpack cached states including:
+        1) output memory from previous chunks in the lower layer;
+        2) attention key and value of left context from proceeding chunk's
+        computation.
+        """
+        past_length = state[3][0][0].item()
+        past_left_context_length = min(self.left_context_length, past_length)
+        past_memory_length = min(
+            self.max_memory_size, math.ceil(past_length / self.chunk_length)
+        )
+        memory_start_idx = self.max_memory_size - past_memory_length
+        pre_memory = state[0][memory_start_idx:]
+        left_context_start_idx = (
+            self.left_context_length - past_left_context_length
+        )
+        left_context_key = state[1][left_context_start_idx:]
+        left_context_val = state[2][left_context_start_idx:]
+        return pre_memory, left_context_key, left_context_val
+
+    def _pack_state(
+        self,
+        next_key: torch.Tensor,
+        next_val: torch.Tensor,
+        update_length: int,
+        memory: torch.Tensor,
+        state: List[torch.Tensor],
+    ) -> List[torch.Tensor]:
+        """Pack updated states including:
+        1) output memory of current chunk in the lower layer;
+        2) attention key and value in current chunk's computation, which would
+        be resued in next chunk's computation.
+        3) length of current chunk.
+        """
+        new_memory = torch.cat([state[0], memory])
+        new_key = torch.cat([state[1], next_key])
+        new_val = torch.cat([state[2], next_val])
+        memory_start_idx = new_memory.size(0) - self.max_memory_size
+        state[0] = new_memory[memory_start_idx:]
+        key_start_idx = new_key.size(0) - self.left_context_length
+        state[1] = new_key[key_start_idx:]
+        val_start_idx = new_val.size(0) - self.left_context_length
+        state[2] = new_val[val_start_idx:]
+        state[3] = state[3] + update_length
+        return state
+
+    def _apply_conv_module_forward(
+        self,
+        right_context_utterance: torch.Tensor,
+        R: int,
+    ) -> torch.Tensor:
+        """Apply convolution module in training and validation mode."""
+        utterance = right_context_utterance[R:]
+        right_context = right_context_utterance[:R]
+        utterance, right_context, _ = self.conv_module(utterance, right_context)
+        right_context_utterance = torch.cat([right_context, utterance])
+        return right_context_utterance
+
+    def _apply_conv_module_infer(
+        self,
+        right_context_utterance: torch.Tensor,
+        R: int,
+        conv_cache: Optional[torch.Tensor] = None,
+    ) -> torch.Tensor:
+        """Apply convolution module on utterance in inference mode."""
+        utterance = right_context_utterance[R:]
+        right_context = right_context_utterance[:R]
+        utterance, right_context, conv_cache = self.conv_module.infer(
+            utterance, right_context, conv_cache
+        )
+        right_context_utterance = torch.cat([right_context, utterance])
+        return right_context_utterance, conv_cache
+
+    def _apply_attention_module_forward(
+        self,
+        right_context_utterance: torch.Tensor,
+        R: int,
+        lengths: torch.Tensor,
+        memory: torch.Tensor,
+        pos_emb: torch.Tensor,
+        attention_mask: Optional[torch.Tensor] = None,
+    ) -> Tuple[torch.Tensor, torch.Tensor]:
+        """Apply attention module in training and validation mode."""
+        if attention_mask is None:
+            raise ValueError(
+                "attention_mask must be not None in training or validation mode."  # noqa
+            )
+        utterance = right_context_utterance[R:]
+        right_context = right_context_utterance[:R]
+
+        if self.use_memory:
+            summary = self.summary_op(utterance.permute(1, 2, 0)).permute(
+                2, 0, 1
+            )
+        else:
+            summary = torch.empty(0).to(
+                dtype=utterance.dtype, device=utterance.device
+            )
+        output_right_context_utterance, output_memory = self.attention(
+            utterance=utterance,
+            lengths=lengths,
+            right_context=right_context,
+            summary=summary,
+            memory=memory,
+            attention_mask=attention_mask,
+            pos_emb=pos_emb,
+        )
+
+        return output_right_context_utterance, output_memory
+
+    def _apply_attention_module_infer(
+        self,
+        right_context_utterance: torch.Tensor,
+        R: int,
+        lengths: torch.Tensor,
+        memory: torch.Tensor,
+        pos_emb: torch.Tensor,
+        state: Optional[List[torch.Tensor]] = None,
+    ) -> Tuple[torch.Tensor, torch.Tensor, List[torch.Tensor]]:
+        """Apply attention module in inference mode.
+        1) Unpack cached states including:
+           - memory from previous chunks in the lower layer;
+           - attention key and value of left context from proceeding
+             chunk's compuation;
+        2) Apply attention computation;
+        3) Pack updated states including:
+           - output memory of current chunk in the lower layer;
+           - attention key and value in current chunk's computation, which would
+             be resued in next chunk's computation.
+           - length of current chunk.
+        """
+        utterance = right_context_utterance[R:]
+        right_context = right_context_utterance[:R]
+
+        if state is None:
+            state = self._init_state(utterance.size(1), device=utterance.device)
+        pre_memory, left_context_key, left_context_val = self._unpack_state(
+            state
+        )
+        if self.use_memory:
+            summary = self.summary_op(utterance.permute(1, 2, 0)).permute(
+                2, 0, 1
+            )
+            summary = summary[:1]
+        else:
+            summary = torch.empty(0).to(
+                dtype=utterance.dtype, device=utterance.device
+            )
+        # pos_emb is of shape [PE, D], where PE = L + 2 * U - 1,
+        # for query of [utterance] (i), key-value [left_context, utterance] (j),
+        # the max relative distance i - j is L + U - 1
+        # the min relative distance i - j is -(U - 1)
+        L = left_context_key.size(0)  # L <= left_context_length
+        U = utterance.size(0)
+        PE = L + 2 * U - 1
+        tot_PE = self.left_context_length + 2 * U - 1
+        assert pos_emb.size(0) == tot_PE
+        pos_emb = pos_emb[tot_PE - PE :]
+        (
+            output_right_context_utterance,
+            output_memory,
+            next_key,
+            next_val,
+        ) = self.attention.infer(
+            utterance=utterance,
+            lengths=lengths,
+            right_context=right_context,
+            summary=summary,
+            memory=pre_memory,
+            left_context_key=left_context_key,
+            left_context_val=left_context_val,
+            pos_emb=pos_emb,
+        )
+        state = self._pack_state(
+            next_key, next_val, utterance.size(0), memory, state
+        )
+        return output_right_context_utterance, output_memory, state
+
+    def forward(
+        self,
+        utterance: torch.Tensor,
+        lengths: torch.Tensor,
+        right_context: torch.Tensor,
+        memory: torch.Tensor,
+        attention_mask: torch.Tensor,
+        pos_emb: torch.Tensor,
+        warmup: float = 1.0,
+    ) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
+        r"""Forward pass for training and validation mode.
+
+        B: batch size;
+        D: embedding dimension;
+        R: length of hard-copied right contexts;
+        U: length of full utterance;
+        M: length of memory vectors.
+
+        Args:
+          utterance (torch.Tensor):
+            Utterance frames, with shape (U, B, D).
+          lengths (torch.Tensor):
+            With shape (B,) and i-th element representing
+            number of valid frames for i-th batch element in utterance.
+          right_context (torch.Tensor):
+            Right context frames, with shape (R, B, D).
+          memory (torch.Tensor):
+            Memory elements, with shape (M, B, D).
+            It is an empty tensor without using memory.
+          attention_mask (torch.Tensor):
+            Attention mask for underlying attention module,
+            with shape (Q, KV), where Q = R + U + S, KV = M + R + U.
+          pos_emb (torch.Tensor):
+            Position encoding embedding, with shape (PE, D).
+            For training mode, P = 2*U-1.
+
+        Returns:
+          A tuple containing 3 tensors:
+            - output utterance, with shape (U, B, D).
+            - output right context, with shape (R, B, D).
+            - output memory, with shape (M, B, D).
+        """
+        R = right_context.size(0)
+        src = torch.cat([right_context, utterance])
+        src_orig = src
+
+        warmup_scale = min(0.1 + warmup, 1.0)
+        # alpha = 1.0 means fully use this encoder layer, 0.0 would mean
+        # completely bypass it.
+        if self.training:
+            alpha = (
+                warmup_scale
+                if torch.rand(()).item() <= (1.0 - self.layer_dropout)
+                else 0.1
+            )
+        else:
+            alpha = 1.0
+
+        # macaron style feed forward module
+        src = src + self.dropout(self.feed_forward_macaron(src))
+
+        # emformer attention module
+        src_att, output_memory = self._apply_attention_module_forward(
+            src, R, lengths, memory, pos_emb, attention_mask
+        )
+        src = src + self.dropout(src_att)
+
+        # convolution module
+        src_conv = self._apply_conv_module_forward(src, R)
+        src = src + self.dropout(src_conv)
+
+        # feed forward module
+        src = src + self.dropout(self.feed_forward(src))
+
+        src = self.norm_final(self.balancer(src))
+
+        if alpha != 1.0:
+            src = alpha * src + (1 - alpha) * src_orig
+
+        output_utterance = src[R:]
+        output_right_context = src[:R]
+        return output_utterance, output_right_context, output_memory
+
+    @torch.jit.export
+    def infer(
+        self,
+        utterance: torch.Tensor,
+        lengths: torch.Tensor,
+        right_context: torch.Tensor,
+        memory: torch.Tensor,
+        pos_emb: torch.Tensor,
+        state: Optional[List[torch.Tensor]] = None,
+        conv_cache: Optional[torch.Tensor] = None,
+    ) -> Tuple[torch.Tensor, torch.Tensor, List[torch.Tensor], torch.Tensor]:
+        """Forward pass for inference.
+
+         B: batch size;
+         D: embedding dimension;
+         R: length of right_context;
+         U: length of utterance;
+         M: length of memory.
+
+        Args:
+           utterance (torch.Tensor):
+             Utterance frames, with shape (U, B, D).
+           lengths (torch.Tensor):
+             With shape (B,) and i-th element representing
+             number of valid frames for i-th batch element in utterance.
+           right_context (torch.Tensor):
+             Right context frames, with shape (R, B, D).
+           memory (torch.Tensor):
+             Memory elements, with shape (M, B, D).
+           state (List[torch.Tensor], optional):
+             List of tensors representing layer internal state generated in
+             preceding computation. (default=None)
+           pos_emb (torch.Tensor):
+             Position encoding embedding, with shape (PE, D).
+             For infer mode, PE = L+2*U-1.
+           conv_cache (torch.Tensor, optional):
+             Cache tensor of left context for causal convolution.
+
+         Returns:
+           (Tensor, Tensor, List[torch.Tensor], Tensor):
+             - output utterance, with shape (U, B, D);
+             - output right_context, with shape (R, B, D);
+             - output memory, with shape (1, B, D) or (0, B, D).
+             - output state.
+             - updated conv_cache.
+        """
+        R = right_context.size(0)
+        src = torch.cat([right_context, utterance])
+
+        # macaron style feed forward module
+        src = src + self.dropout(self.feed_forward_macaron(src))
+
+        # emformer attention module
+        (
+            src_att,
+            output_memory,
+            output_state,
+        ) = self._apply_attention_module_infer(
+            src, R, lengths, memory, pos_emb, state
+        )
+        src = src + self.dropout(src_att)
+
+        # convolution module
+        src_conv, conv_cache = self._apply_conv_module_infer(src, R, conv_cache)
+        src = src + self.dropout(src_conv)
+
+        # feed forward module
+        src = src + self.dropout(self.feed_forward(src))
+
+        src = self.norm_final(self.balancer(src))
+
+        output_utterance = src[R:]
+        output_right_context = src[:R]
+        return (
+            output_utterance,
+            output_right_context,
+            output_memory,
+            output_state,
+            conv_cache,
+        )
diff --git a/egs/librispeech/ASR/conv_emformer_transducer_stateless/test_emformer.py b/egs/librispeech/ASR/conv_emformer_transducer_stateless/test_emformer.py
index 4549dad22..d8913ef74 100644
--- a/egs/librispeech/ASR/conv_emformer_transducer_stateless/test_emformer.py
+++ b/egs/librispeech/ASR/conv_emformer_transducer_stateless/test_emformer.py
@@ -154,9 +154,131 @@ def test_convolution_module_infer():
     assert new_cache.shape == (B, D, kernel_size - 1)
 
 
+def test_emformer_encoder_layer_forward():
+    from emformer import EmformerEncoderLayer
+
+    B, D = 2, 256
+    chunk_length = 8
+    right_context_length = 2
+    left_context_length = 8
+    kernel_size = 31
+    num_chunks = 3
+    U = num_chunks * chunk_length
+    R = num_chunks * right_context_length
+
+    for use_memory in [True, False]:
+        if use_memory:
+            S = num_chunks
+            M = S - 1
+        else:
+            S, M = 0, 0
+
+        layer = EmformerEncoderLayer(
+            d_model=D,
+            nhead=8,
+            dim_feedforward=1024,
+            chunk_length=chunk_length,
+            cnn_module_kernel=kernel_size,
+            left_context_length=left_context_length,
+            right_context_length=right_context_length,
+            max_memory_size=M,
+        )
+
+        Q, KV = R + U + S, M + R + U
+        utterance = torch.randn(U, B, D)
+        lengths = torch.randint(1, U + 1, (B,))
+        lengths[0] = U
+        right_context = torch.randn(R, B, D)
+        memory = torch.randn(M, B, D)
+        attention_mask = torch.rand(Q, KV) >= 0.5
+        PE = 2 * U - 1
+        pos_emb = torch.randn(PE, D)
+
+        output_utterance, output_right_context, output_memory = layer(
+            utterance,
+            lengths,
+            right_context,
+            memory,
+            attention_mask,
+            pos_emb,
+        )
+        assert output_utterance.shape == (U, B, D)
+        assert output_right_context.shape == (R, B, D)
+        assert output_memory.shape == (M, B, D)
+
+
+def test_emformer_encoder_layer_infer():
+    from emformer import EmformerEncoderLayer
+
+    B, D = 2, 256
+    chunk_length = 8
+    right_context_length = 2
+    left_context_length = 8
+    kernel_size = 31
+    num_chunks = 1
+    U = num_chunks * chunk_length
+    R = num_chunks * right_context_length
+
+    for use_memory in [True, False]:
+        if use_memory:
+            M = 3
+        else:
+            M = 0
+
+        layer = EmformerEncoderLayer(
+            d_model=D,
+            nhead=8,
+            dim_feedforward=1024,
+            chunk_length=chunk_length,
+            cnn_module_kernel=kernel_size,
+            left_context_length=left_context_length,
+            right_context_length=right_context_length,
+            max_memory_size=M,
+        )
+
+        utterance = torch.randn(U, B, D)
+        lengths = torch.randint(1, U + 1, (B,))
+        lengths[0] = U
+        right_context = torch.randn(R, B, D)
+        memory = torch.randn(M, B, D)
+        state = None
+        PE = left_context_length + 2 * U - 1
+        pos_emb = torch.randn(PE, D)
+        conv_cache = None
+        (
+            output_utterance,
+            output_right_context,
+            output_memory,
+            output_state,
+            conv_cache,
+        ) = layer.infer(
+            utterance,
+            lengths,
+            right_context,
+            memory,
+            pos_emb,
+            state,
+            conv_cache,
+        )
+        assert output_utterance.shape == (U, B, D)
+        assert output_right_context.shape == (R, B, D)
+        if use_memory:
+            assert output_memory.shape == (1, B, D)
+        else:
+            assert output_memory.shape == (0, B, D)
+        assert len(output_state) == 4
+        assert output_state[0].shape == (M, B, D)
+        assert output_state[1].shape == (left_context_length, B, D)
+        assert output_state[2].shape == (left_context_length, B, D)
+        assert output_state[3].shape == (1, B)
+        assert conv_cache.shape == (B, D, kernel_size - 1)
+
+
 if __name__ == "__main__":
     test_rel_positional_encoding()
     test_emformer_attention_forward()
     test_emformer_attention_infer()
     test_convolution_module_forward()
     test_convolution_module_infer()
+    test_emformer_encoder_layer_forward()
+    test_emformer_encoder_layer_infer()