diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52a67f64af..93db4fe211 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Replaced `load_boston` with `load_diabetes` in the docs and tests ([#629](https://github.com/PyTorchLightning/lightning-bolts/pull/629))
 
 
+- Added base encoder and MLP dimension arguments to BYOL constructor ([#637](https://github.com/PyTorchLightning/lightning-bolts/pull/637))
+
+
 ### Deprecated
 
 
diff --git a/pl_bolts/models/self_supervised/byol/byol_module.py b/pl_bolts/models/self_supervised/byol/byol_module.py
index 3107a1956f..514e6e2964 100644
--- a/pl_bolts/models/self_supervised/byol/byol_module.py
+++ b/pl_bolts/models/self_supervised/byol/byol_module.py
@@ -1,6 +1,6 @@
 from argparse import ArgumentParser
 from copy import deepcopy
-from typing import Any
+from typing import Any, Union
 
 import pytorch_lightning as pl
 import torch
@@ -72,6 +72,10 @@ def __init__(
         num_workers: int = 0,
         warmup_epochs: int = 10,
         max_epochs: int = 1000,
+        base_encoder: Union[str, torch.nn.Module] = 'resnet50',
+        encoder_out_dim: int = 2048,
+        projector_hidden_size: int = 4096,
+        projector_out_dim: int = 256,
         **kwargs
     ):
         """
@@ -84,11 +88,15 @@ def __init__(
             num_workers: number of workers
             warmup_epochs: num of epochs for scheduler warm up
             max_epochs: max epochs for scheduler
+            base_encoder: the base encoder module or resnet name
+            encoder_out_dim: output dimension of base_encoder
+            projector_hidden_size: hidden layer size of projector MLP
+            projector_out_dim: output size of projector MLP
         """
         super().__init__()
-        self.save_hyperparameters()
+        self.save_hyperparameters(ignore='base_encoder')
 
-        self.online_network = SiameseArm()
+        self.online_network = SiameseArm(base_encoder, encoder_out_dim, projector_hidden_size, projector_out_dim)
         self.target_network = deepcopy(self.online_network)
         self.weight_callback = BYOLMAWeightUpdate()
 
diff --git a/pl_bolts/models/self_supervised/byol/models.py b/pl_bolts/models/self_supervised/byol/models.py
index 53b90bf6ef..d7e5e87a29 100644
--- a/pl_bolts/models/self_supervised/byol/models.py
+++ b/pl_bolts/models/self_supervised/byol/models.py
@@ -23,17 +23,17 @@ def forward(self, x):
 
 class SiameseArm(nn.Module):
 
-    def __init__(self, encoder=None):
+    def __init__(self, encoder='resnet50', encoder_out_dim=2048, projector_hidden_size=4096, projector_out_dim=256):
         super().__init__()
 
-        if encoder is None:
-            encoder = torchvision_ssl_encoder('resnet50')
+        if isinstance(encoder, str):
+            encoder = torchvision_ssl_encoder(encoder)
         # Encoder
         self.encoder = encoder
         # Projector
-        self.projector = MLP()
+        self.projector = MLP(encoder_out_dim, projector_hidden_size, projector_out_dim)
         # Predictor
-        self.predictor = MLP(input_dim=256)
+        self.predictor = MLP(projector_out_dim, projector_hidden_size, projector_out_dim)
 
     def forward(self, x):
         y = self.encoder(x)[0]