diff --git a/transport/grpc/_grpc_test/context_metadata.go b/transport/grpc/_grpc_test/context_metadata.go
index 5bd545d..0769325 100644
--- a/transport/grpc/_grpc_test/context_metadata.go
+++ b/transport/grpc/_grpc_test/context_metadata.go
@@ -38,8 +38,8 @@
 
 /* server before functions */
 
-func extractCorrelationID(ctx context.Context, md *metadata.MD) context.Context {
-	if hdr, ok := (*md)[string(correlationID)]; ok {
+func extractCorrelationID(ctx context.Context, md metadata.MD) context.Context {
+	if hdr, ok := md[string(correlationID)]; ok {
 		cID := hdr[len(hdr)-1]
 		ctx = context.WithValue(ctx, correlationID, cID)
 		fmt.Printf("\tServer received correlationID %q in metadata header, set context\n", cID)
@@ -47,10 +47,10 @@
 	return ctx
 }
 
-func displayServerRequestHeaders(ctx context.Context, md *metadata.MD) context.Context {
-	if len(*md) > 0 {
+func displayServerRequestHeaders(ctx context.Context, md metadata.MD) context.Context {
+	if len(md) > 0 {
 		fmt.Println("\tServer << Request Headers:")
-		for key, val := range *md {
+		for key, val := range md {
 			fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
 		}
 	}
@@ -59,37 +59,42 @@
 
 /* server after functions */
 
-func injectResponseHeader(ctx context.Context, md *metadata.MD, _ *metadata.MD) {
+func injectResponseHeader(ctx context.Context, md *metadata.MD, _ *metadata.MD) context.Context {
 	*md = metadata.Join(*md, metadata.Pairs(string(responseHDR), "has-a-value"))
+	return ctx
 }
 
-func displayServerResponseHeaders(ctx context.Context, md *metadata.MD, _ *metadata.MD) {
+func displayServerResponseHeaders(ctx context.Context, md *metadata.MD, _ *metadata.MD) context.Context {
 	if len(*md) > 0 {
 		fmt.Println("\tServer >> Response Headers:")
 		for key, val := range *md {
 			fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
 		}
 	}
+	return ctx
 }
 
-func injectResponseTrailer(ctx context.Context, _ *metadata.MD, md *metadata.MD) {
+func injectResponseTrailer(ctx context.Context, _ *metadata.MD, md *metadata.MD) context.Context {
 	*md = metadata.Join(*md, metadata.Pairs(string(responseTRLR), "has-a-value-too"))
+	return ctx
 }
 
-func injectConsumedCorrelationID(ctx context.Context, _ *metadata.MD, md *metadata.MD) {
+func injectConsumedCorrelationID(ctx context.Context, _ *metadata.MD, md *metadata.MD) context.Context {
 	if hdr, ok := ctx.Value(correlationID).(string); ok {
 		fmt.Printf("\tServer found correlationID %q in context, set consumed trailer\n", hdr)
 		*md = metadata.Join(*md, metadata.Pairs(string(correlationIDTRLR), hdr))
 	}
+	return ctx
 }
 
-func displayServerResponseTrailers(ctx context.Context, _ *metadata.MD, md *metadata.MD) {
+func displayServerResponseTrailers(ctx context.Context, _ *metadata.MD, md *metadata.MD) context.Context {
 	if len(*md) > 0 {
 		fmt.Println("\tServer >> Response Trailers:")
 		for key, val := range *md {
 			fmt.Printf("\t\t%s: %s\n", key, val[len(val)-1])
 		}
 	}
+	return ctx
 }
 
 /* client after functions */
diff --git a/transport/grpc/client.go b/transport/grpc/client.go
index 622ca88..c0faa2b 100644
--- a/transport/grpc/client.go
+++ b/transport/grpc/client.go
@@ -21,7 +21,7 @@
 	enc         EncodeRequestFunc
 	dec         DecodeResponseFunc
 	grpcReply   reflect.Type
-	before      []RequestFunc
+	before      []ClientRequestFunc
 	after       []ClientResponseFunc
 }
 
@@ -54,7 +54,7 @@
 				reflect.ValueOf(grpcReply),
 			).Interface(),
 		),
-		before: []RequestFunc{},
+		before: []ClientRequestFunc{},
 		after:  []ClientResponseFunc{},
 	}
 	for _, option := range options {
@@ -68,7 +68,7 @@
 
 // ClientBefore sets the RequestFuncs that are applied to the outgoing gRPC
 // request before it's invoked.
-func ClientBefore(before ...RequestFunc) ClientOption {
+func ClientBefore(before ...ClientRequestFunc) ClientOption {
 	return func(c *Client) { c.before = append(c.before, before...) }
 }
 
diff --git a/transport/grpc/request_response_funcs.go b/transport/grpc/request_response_funcs.go
index 05a9d34..8d072ed 100644
--- a/transport/grpc/request_response_funcs.go
+++ b/transport/grpc/request_response_funcs.go
@@ -12,17 +12,22 @@
 	binHdrSuffix = "-bin"
 )
 
-// RequestFunc may take information from a gRPC request and put it into a
-// request context. In Servers, RequestFuncs are executed prior to invoking the
-// endpoint. In Clients, RequestFuncs are executed after creating the request
-// but prior to invoking the gRPC client.
-type RequestFunc func(context.Context, *metadata.MD) context.Context
+// ClientRequestFunc may take information from context and use it to construct
+// metadata headers to be transported to the server. ClientRequestFuncs are
+// executed after creating the request but prior to sending the gRPC request to
+// the server.
+type ClientRequestFunc func(context.Context, *metadata.MD) context.Context
+
+// ServerRequestFunc may take information from the received metadata header and
+// use it to place items in the request scoped context. ServerRequestFuncs are
+// executed prior to invoking the endpoint.
+type ServerRequestFunc func(context.Context, metadata.MD) context.Context
 
 // ServerResponseFunc may take information from a request context and use it to
 // manipulate the gRPC response metadata headers and trailers. ResponseFuncs are
 // only executed in servers, after invoking the endpoint but prior to writing a
 // response.
-type ServerResponseFunc func(ctx context.Context, header *metadata.MD, trailer *metadata.MD)
+type ServerResponseFunc func(ctx context.Context, header *metadata.MD, trailer *metadata.MD) context.Context
 
 // ClientResponseFunc may take information from a gRPC metadata header and/or
 // trailer and make the responses available for consumption. ClientResponseFuncs
@@ -30,9 +35,9 @@
 // being decoded.
 type ClientResponseFunc func(ctx context.Context, header metadata.MD, trailer metadata.MD) context.Context
 
-// SetRequestHeader returns a RequestFunc that sets the specified metadata
+// SetRequestHeader returns a ClientRequestFunc that sets the specified metadata
 // key-value pair.
-func SetRequestHeader(key, val string) RequestFunc {
+func SetRequestHeader(key, val string) ClientRequestFunc {
 	return func(ctx context.Context, md *metadata.MD) context.Context {
 		key, val := EncodeKeyValue(key, val)
 		(*md)[key] = append((*md)[key], val)
@@ -43,18 +48,20 @@
 // SetResponseHeader returns a ResponseFunc that sets the specified metadata
 // key-value pair.
 func SetResponseHeader(key, val string) ServerResponseFunc {
-	return func(_ context.Context, md *metadata.MD, _ *metadata.MD) {
+	return func(ctx context.Context, md *metadata.MD, _ *metadata.MD) context.Context {
 		key, val := EncodeKeyValue(key, val)
 		(*md)[key] = append((*md)[key], val)
+		return ctx
 	}
 }
 
 // SetResponseTrailer returns a ResponseFunc that sets the specified metadata
 // key-value pair.
 func SetResponseTrailer(key, val string) ServerResponseFunc {
-	return func(_ context.Context, _ *metadata.MD, md *metadata.MD) {
+	return func(ctx context.Context, _ *metadata.MD, md *metadata.MD) context.Context {
 		key, val := EncodeKeyValue(key, val)
 		(*md)[key] = append((*md)[key], val)
+		return ctx
 	}
 }
 
diff --git a/transport/grpc/server.go b/transport/grpc/server.go
index 476902e..b14d7d8 100644
--- a/transport/grpc/server.go
+++ b/transport/grpc/server.go
@@ -21,7 +21,7 @@
 	e      endpoint.Endpoint
 	dec    DecodeRequestFunc
 	enc    EncodeResponseFunc
-	before []RequestFunc
+	before []ServerRequestFunc
 	after  []ServerResponseFunc
 	logger log.Logger
 }
@@ -54,7 +54,7 @@
 
 // ServerBefore functions are executed on the HTTP request object before the
 // request is decoded.
-func ServerBefore(before ...RequestFunc) ServerOption {
+func ServerBefore(before ...ServerRequestFunc) ServerOption {
 	return func(s *Server) { s.before = append(s.before, before...) }
 }
 
@@ -79,11 +79,8 @@
 	}
 
 	for _, f := range s.before {
-		ctx = f(ctx, &md)
+		ctx = f(ctx, md)
 	}
-
-	// Store potentially updated metadata in the gRPC context.
-	ctx = metadata.NewContext(ctx, md)
 
 	request, err := s.dec(ctx, req)
 	if err != nil {
@@ -99,7 +96,7 @@
 
 	var mdHeader, mdTrailer metadata.MD
 	for _, f := range s.after {
-		f(ctx, &mdHeader, &mdTrailer)
+		ctx = f(ctx, &mdHeader, &mdTrailer)
 	}
 
 	grpcResp, err := s.enc(ctx, response)