diff --git a/rendezvous/client.go b/rendezvous/client.go
index 15dbf48b..1ff3f3d1 100644
--- a/rendezvous/client.go
+++ b/rendezvous/client.go
@@ -13,6 +13,7 @@ import (
 	"github.com/gorilla/websocket"
 	"github.com/psanford/wormhole-william/internal/crypto"
 	"github.com/psanford/wormhole-william/rendezvous/internal/msgs"
+	"github.com/psanford/wormhole-william/version"
 )
 
 // NewClient returns a Rendezvous client. URL is the websocket
@@ -21,8 +22,8 @@ import (
 // AppID is the application identity string of the client.
 //
 // Two clients can only communicate if they have the same AppID.
-func NewClient(url, sideID, appID string) *Client {
-	return &Client{
+func NewClient(url, sideID, appID string, opts ...ClientOption) *Client {
+	c := &Client{
 		url:         url,
 		sideID:      sideID,
 		appID:       appID,
@@ -33,6 +34,12 @@ func NewClient(url, sideID, appID string) *Client {
 
 		pendingMsgWaiters: make(map[uint32]chan uint32),
 	}
+
+	for _, opt := range opts {
+		opt.setValue(c)
+	}
+
+	return c
 }
 
 type pendingMsg struct {
@@ -52,6 +59,9 @@ type Client struct {
 
 	nameplate string
 
+	agentString  string
+	agentVersion string
+
 	wsClient *websocket.Conn
 
 	mailboxMsgs           []MailboxEvent
@@ -511,10 +521,26 @@ func (c *Client) prepareMsg(msg interface{}) (string, error) {
 	return id, nil
 }
 
+func (c *Client) agentID() (string, string) {
+	agent := c.agentString
+	if agent == "" {
+		agent = version.AgentString
+	}
+	v := c.agentVersion
+	if v == "" {
+		v = version.AgentVersion
+	}
+
+	return agent, v
+}
+
 func (c *Client) bind(ctx context.Context, side, appID string) error {
+	agent, version := c.agentID()
+
 	bind := msgs.Bind{
-		Side:  side,
-		AppID: appID,
+		Side:          side,
+		AppID:         appID,
+		ClientVersion: []string{agent, version},
 	}
 
 	_, err := c.sendAndWait(ctx, &bind)
diff --git a/rendezvous/client_test.go b/rendezvous/client_test.go
index 4a7dcf79..2c990f22 100644
--- a/rendezvous/client_test.go
+++ b/rendezvous/client_test.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/psanford/wormhole-william/internal/crypto"
 	"github.com/psanford/wormhole-william/rendezvous/rendezvousservertest"
+	"github.com/psanford/wormhole-william/version"
 )
 
 func TestBasicClient(t *testing.T) {
@@ -30,6 +31,15 @@ func TestBasicClient(t *testing.T) {
 		t.Fatalf("MOTD got=%s expected=%s", info.MOTD, rendezvousservertest.TestMotd)
 	}
 
+	gotAgents := ts.Agents()
+	expectAgents := [][]string{
+		[]string{version.AgentString, version.AgentVersion},
+	}
+
+	if !reflect.DeepEqual(gotAgents, expectAgents) {
+		t.Fatalf("got agents=%v expected=%v", gotAgents, expectAgents)
+	}
+
 	nameplate, err := c0.CreateMailbox(ctx)
 	if err != nil {
 		t.Fatal(err)
@@ -100,3 +110,33 @@ func TestBasicClient(t *testing.T) {
 	default:
 	}
 }
+
+func TestCustomUserAgent(t *testing.T) {
+	ts := rendezvousservertest.NewServer()
+	defer ts.Close()
+
+	side0 := crypto.RandSideID()
+	appID := "nightclubs-reasonableness"
+
+	agentString := "deafening-buttermilk"
+	agentVersion := "v1.2.3"
+	c0 := NewClient(ts.WebSocketURL(), side0, appID, WithVersion(agentString, agentVersion))
+
+	ctx := context.Background()
+
+	_, err := c0.Connect(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	gotAgents := ts.Agents()
+	expectAgents := [][]string{
+		[]string{agentString, agentVersion},
+	}
+
+	if !reflect.DeepEqual(gotAgents, expectAgents) {
+		t.Fatalf("got agents=%v expected=%v", gotAgents, expectAgents)
+	}
+
+	c0.Close(ctx, "")
+}
diff --git a/rendezvous/internal/msgs/msgs.go b/rendezvous/internal/msgs/msgs.go
index 9da619a7..0e3765db 100644
--- a/rendezvous/internal/msgs/msgs.go
+++ b/rendezvous/internal/msgs/msgs.go
@@ -19,6 +19,9 @@ type Bind struct {
 	ID    string `json:"id"`
 	Side  string `json:"side"`
 	AppID string `json:"appid"`
+	// ClientVersion is by convention a two value array
+	// of [client_id, version]
+	ClientVersion []string `json:"client_version"`
 }
 
 // Client sent aollocate message
diff --git a/rendezvous/options.go b/rendezvous/options.go
new file mode 100644
index 00000000..75774466
--- /dev/null
+++ b/rendezvous/options.go
@@ -0,0 +1,24 @@
+package rendezvous
+
+type ClientOption interface {
+	setValue(*Client)
+}
+
+type versionOption struct {
+	agentString  string
+	agentVersion string
+}
+
+func (o *versionOption) setValue(c *Client) {
+	c.agentString = o.agentString
+	c.agentVersion = o.agentVersion
+}
+
+// WithVersion returns a ClientOption to override the default client
+// identifier and version reported to the rendezvous server.
+func WithVersion(agentID string, version string) ClientOption {
+	return &versionOption{
+		agentString:  agentID,
+		agentVersion: version,
+	}
+}
diff --git a/rendezvous/rendezvousservertest/rendezvousservertest.go b/rendezvous/rendezvousservertest/rendezvousservertest.go
index cfb7e733..ffdbae50 100644
--- a/rendezvous/rendezvousservertest/rendezvousservertest.go
+++ b/rendezvous/rendezvousservertest/rendezvousservertest.go
@@ -25,6 +25,7 @@ type TestServer struct {
 	mu         sync.Mutex
 	mailboxes  map[string]*mailbox
 	nameplates map[int16]string
+	agents     [][]string
 }
 
 func NewServer() *TestServer {
@@ -40,6 +41,10 @@ func NewServer() *TestServer {
 	return ts
 }
 
+func (ts *TestServer) Agents() [][]string {
+	return ts.agents
+}
+
 func (ts *TestServer) WebSocketURL() string {
 	u, err := url.Parse(ts.URL)
 	if err != nil {
@@ -236,6 +241,10 @@ func (ts *TestServer) handleWS(w http.ResponseWriter, r *http.Request) {
 				continue
 			}
 
+			ts.mu.Lock()
+			ts.agents = append(ts.agents, m.ClientVersion)
+			ts.mu.Unlock()
+
 			sideID = m.Side
 		case *msgs.Allocate:
 			ackMsg(m.ID)
diff --git a/version/version.go b/version/version.go
new file mode 100644
index 00000000..5d1b7d71
--- /dev/null
+++ b/version/version.go
@@ -0,0 +1,8 @@
+package version
+
+var (
+	// Default Agent identifier sent to rendezvous server
+	AgentString = "go-william"
+	// Default Agent version sent to rendezvous server
+	AgentVersion = "v1.0.0"
+)