diff --git a/include/caffe/net.hpp b/include/caffe/net.hpp
index 1d06dc45..bbb220eb 100644
--- a/include/caffe/net.hpp
+++ b/include/caffe/net.hpp
@@ -89,7 +89,7 @@ class Net {
    * @brief For an already initialized net, implicitly copies (i.e., using no
    *        additional memory) the pre-trained layers from another Net.
    */
-  void ShareTrainedLayersWith(Net* other);
+  void ShareTrainedLayersWith(const Net* other);
   // For an already initialized net, CopyTrainedLayersFrom() copies the already
   // trained layers from another net parameter instance.
   /**
@@ -99,51 +99,73 @@ class Net {
   void CopyTrainedLayersFrom(const NetParameter& param);
   void CopyTrainedLayersFrom(const string trained_filename);
   /// @brief Writes the net to a proto.
-  void ToProto(NetParameter* param, bool write_diff = false);
+  void ToProto(NetParameter* param, bool write_diff = false) const;
 
   /// @brief returns the network name.
-  inline const string& name() { return name_; }
+  inline const string& name() const { return name_; }
   /// @brief returns the layer names
-  inline const vector<string>& layer_names() { return layer_names_; }
+  inline const vector<string>& layer_names() const { return layer_names_; }
   /// @brief returns the blob names
-  inline const vector<string>& blob_names() { return blob_names_; }
+  inline const vector<string>& blob_names() const { return blob_names_; }
   /// @brief returns the blobs
-  inline const vector<shared_ptr<Blob<Dtype> > >& blobs() { return blobs_; }
+  inline const vector<shared_ptr<Blob<Dtype> > >& blobs() const {
+    return blobs_;
+  }
   /// @brief returns the layers
-  inline const vector<shared_ptr<Layer<Dtype> > >& layers() { return layers_; }
+  inline const vector<shared_ptr<Layer<Dtype> > >& layers() const {
+    return layers_;
+  }
   /**
    * @brief returns the bottom vecs for each layer -- usually you won't
    *        need this unless you do per-layer checks such as gradients.
    */
-  inline vector<vector<Blob<Dtype>*> >& bottom_vecs() { return bottom_vecs_; }
+  inline const vector<vector<Blob<Dtype>*> >& bottom_vecs() const {
+    return bottom_vecs_;
+  }
   /**
    * @brief returns the top vecs for each layer -- usually you won't
    *        need this unless you do per-layer checks such as gradients.
    */
-  inline vector<vector<Blob<Dtype>*> >& top_vecs() { return top_vecs_; }
-  inline vector<vector<bool> >& bottom_need_backward() {
+  inline const vector<vector<Blob<Dtype>*> >& top_vecs() const {
+    return top_vecs_;
+  }
+  inline const vector<vector<bool> >& bottom_need_backward() const {
     return bottom_need_backward_;
   }
-  inline vector<Dtype>& blob_loss_weights() {
+  inline const vector<Dtype>& blob_loss_weights() const {
     return blob_loss_weights_;
   }
   /// @brief returns the parameters
-  inline vector<shared_ptr<Blob<Dtype> > >& params() { return params_; }
+  inline const vector<shared_ptr<Blob<Dtype> > >& params() const {
+    return params_;
+  }
   /// @brief returns the parameter learning rate multipliers
-  inline vector<float>& params_lr() { return params_lr_; }
-  inline vector<float>& params_weight_decay() { return params_weight_decay_; }
-  const map<string, int>& param_names_index() { return param_names_index_; }
+  inline const vector<float>& params_lr() const { return params_lr_; }
+  inline const vector<float>& params_weight_decay() const {
+    return params_weight_decay_;
+  }
+  const map<string, int>& param_names_index() const {
+    return param_names_index_;
+  }
   /// @brief Input and output blob numbers
-  inline int num_inputs() { return net_input_blobs_.size(); }
-  inline int num_outputs() { return net_output_blobs_.size(); }
-  inline vector<Blob<Dtype>*>& input_blobs() { return net_input_blobs_; }
-  inline vector<Blob<Dtype>*>& output_blobs() { return net_output_blobs_; }
-  inline vector<int>& input_blob_indices() { return net_input_blob_indices_; }
-  inline vector<int>& output_blob_indices() { return net_output_blob_indices_; }
-  bool has_blob(const string& blob_name);
-  const shared_ptr<Blob<Dtype> > blob_by_name(const string& blob_name);
-  bool has_layer(const string& layer_name);
-  const shared_ptr<Layer<Dtype> > layer_by_name(const string& layer_name);
+  inline int num_inputs() const { return net_input_blobs_.size(); }
+  inline int num_outputs() const { return net_output_blobs_.size(); }
+  inline const vector<Blob<Dtype>*>& input_blobs() const {
+    return net_input_blobs_;
+  }
+  inline const vector<Blob<Dtype>*>& output_blobs() const {
+    return net_output_blobs_;
+  }
+  inline const vector<int>& input_blob_indices() const {
+    return net_input_blob_indices_;
+  }
+  inline const vector<int>& output_blob_indices() const {
+    return net_output_blob_indices_;
+  }
+  bool has_blob(const string& blob_name) const;
+  const shared_ptr<Blob<Dtype> > blob_by_name(const string& blob_name) const;
+  bool has_layer(const string& layer_name) const;
+  const shared_ptr<Layer<Dtype> > layer_by_name(const string& layer_name) const;
 
   void set_debug_info(const bool value) { debug_info_ = value; }
 
diff --git a/src/caffe/net.cpp b/src/caffe/net.cpp
index e4492cfd..47fc8446 100644
--- a/src/caffe/net.cpp
+++ b/src/caffe/net.cpp
@@ -636,7 +636,7 @@ void Net<Dtype>::UpdateDebugInfo(const int param_id) {
 }
 
 template <typename Dtype>
-void Net<Dtype>::ShareTrainedLayersWith(Net* other) {
+void Net<Dtype>::ShareTrainedLayersWith(const Net* other) {
   int num_source_layers = other->layers().size();
   for (int i = 0; i < num_source_layers; ++i) {
     Layer<Dtype>* source_layer = other->layers()[i].get();
@@ -726,7 +726,7 @@ void Net<Dtype>::CopyTrainedLayersFrom(const string trained_filename) {
 }
 
 template <typename Dtype>
-void Net<Dtype>::ToProto(NetParameter* param, bool write_diff) {
+void Net<Dtype>::ToProto(NetParameter* param, bool write_diff) const {
   param->Clear();
   param->set_name(name_);
   // Add bottom and top
@@ -785,16 +785,16 @@ void Net<Dtype>::Update() {
 }
 
 template <typename Dtype>
-bool Net<Dtype>::has_blob(const string& blob_name) {
+bool Net<Dtype>::has_blob(const string& blob_name) const {
   return blob_names_index_.find(blob_name) != blob_names_index_.end();
 }
 
 template <typename Dtype>
 const shared_ptr<Blob<Dtype> > Net<Dtype>::blob_by_name(
-    const string& blob_name) {
+    const string& blob_name) const {
   shared_ptr<Blob<Dtype> > blob_ptr;
   if (has_blob(blob_name)) {
-    blob_ptr = blobs_[blob_names_index_[blob_name]];
+    blob_ptr = blobs_[blob_names_index_.find(blob_name)->second];
   } else {
     blob_ptr.reset((Blob<Dtype>*)(NULL));
     LOG(WARNING) << "Unknown blob name " << blob_name;
@@ -803,16 +803,16 @@ const shared_ptr<Blob<Dtype> > Net<Dtype>::blob_by_name(
 }
 
 template <typename Dtype>
-bool Net<Dtype>::has_layer(const string& layer_name) {
+bool Net<Dtype>::has_layer(const string& layer_name) const {
   return layer_names_index_.find(layer_name) != layer_names_index_.end();
 }
 
 template <typename Dtype>
 const shared_ptr<Layer<Dtype> > Net<Dtype>::layer_by_name(
-    const string& layer_name) {
+    const string& layer_name) const {
   shared_ptr<Layer<Dtype> > layer_ptr;
   if (has_layer(layer_name)) {
-    layer_ptr = layers_[layer_names_index_[layer_name]];
+    layer_ptr = layers_[layer_names_index_.find(layer_name)->second];
   } else {
     layer_ptr.reset((Layer<Dtype>*)(NULL));
     LOG(WARNING) << "Unknown layer name " << layer_name;
diff --git a/src/caffe/solver.cpp b/src/caffe/solver.cpp
index ab9c00ee..3fa0e2d1 100644
--- a/src/caffe/solver.cpp
+++ b/src/caffe/solver.cpp
@@ -418,7 +418,7 @@ Dtype SGDSolver<Dtype>::GetLearningRate() {
 template <typename Dtype>
 void SGDSolver<Dtype>::PreSolve() {
   // Initialize the history
-  vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
+  const vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
   history_.clear();
   update_.clear();
   temp_.clear();
@@ -439,9 +439,10 @@ void SGDSolver<Dtype>::PreSolve() {
 
 template <typename Dtype>
 void SGDSolver<Dtype>::ComputeUpdateValue() {
-  vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
-  vector<float>& net_params_lr = this->net_->params_lr();
-  vector<float>& net_params_weight_decay = this->net_->params_weight_decay();
+  const vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
+  const vector<float>& net_params_lr = this->net_->params_lr();
+  const vector<float>& net_params_weight_decay =
+      this->net_->params_weight_decay();
   // get the learning rate
   Dtype rate = GetLearningRate();
   if (this->param_.display() && this->iter_ % this->param_.display() == 0) {
@@ -552,9 +553,10 @@ void SGDSolver<Dtype>::RestoreSolverState(const SolverState& state) {
 
 template <typename Dtype>
 void NesterovSolver<Dtype>::ComputeUpdateValue() {
-  vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
-  vector<float>& net_params_lr = this->net_->params_lr();
-  vector<float>& net_params_weight_decay = this->net_->params_weight_decay();
+  const vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
+  const vector<float>& net_params_lr = this->net_->params_lr();
+  const vector<float>& net_params_weight_decay =
+      this->net_->params_weight_decay();
   // get the learning rate
   Dtype rate = this->GetLearningRate();
   if (this->param_.display() && this->iter_ % this->param_.display() == 0) {
@@ -667,9 +669,10 @@ void NesterovSolver<Dtype>::ComputeUpdateValue() {
 
 template <typename Dtype>
 void AdaGradSolver<Dtype>::ComputeUpdateValue() {
-  vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
-  vector<float>& net_params_lr = this->net_->params_lr();
-  vector<float>& net_params_weight_decay = this->net_->params_weight_decay();
+  const vector<shared_ptr<Blob<Dtype> > >& net_params = this->net_->params();
+  const vector<float>& net_params_lr = this->net_->params_lr();
+  const vector<float>& net_params_weight_decay =
+      this->net_->params_weight_decay();
   // get the learning rate
   Dtype rate = this->GetLearningRate();
   Dtype delta = this->param_.delta();
diff --git a/tools/caffe.cpp b/tools/caffe.cpp
index 9f9d975d..ad54bc3b 100644
--- a/tools/caffe.cpp
+++ b/tools/caffe.cpp
@@ -220,8 +220,8 @@ int time() {
   caffe_net.Backward();
 
   const vector<shared_ptr<Layer<float> > >& layers = caffe_net.layers();
-  vector<vector<Blob<float>*> >& bottom_vecs = caffe_net.bottom_vecs();
-  vector<vector<Blob<float>*> >& top_vecs = caffe_net.top_vecs();
+  const vector<vector<Blob<float>*> >& bottom_vecs = caffe_net.bottom_vecs();
+  const vector<vector<Blob<float>*> >& top_vecs = caffe_net.top_vecs();
   const vector<vector<bool> >& bottom_need_backward =
       caffe_net.bottom_need_backward();
   LOG(INFO) << "*** Benchmark begins ***";