diff --git a/gossipsub.go b/gossipsub.go
index 1b2026c..e65f782 100644
--- a/gossipsub.go
+++ b/gossipsub.go
@@ -65,6 +65,7 @@ type GossipSubRouter struct {
 	gossip  map[peer.ID][]*pb.ControlIHave  // pending gossip
 	control map[peer.ID]*pb.ControlMessage  // pending control messages
 	mcache  *MessageCache
+	tracer  *pubsubTracer
 }
 
 func (gs *GossipSubRouter) Protocols() []protocol.ID {
@@ -73,16 +74,21 @@ func (gs *GossipSubRouter) Protocols() []protocol.ID {
 
 func (gs *GossipSubRouter) Attach(p *PubSub) {
 	gs.p = p
+	if p.tracer != nil {
+		gs.tracer = p.tracer
+	}
 	go gs.heartbeatTimer()
 }
 
 func (gs *GossipSubRouter) AddPeer(p peer.ID, proto protocol.ID) {
 	log.Debugf("PEERUP: Add new peer %s using %s", p, proto)
+	gs.tracer.AddPeer(p, proto)
 	gs.peers[p] = proto
 }
 
 func (gs *GossipSubRouter) RemovePeer(p peer.ID) {
 	log.Debugf("PEERDOWN: Remove disconnected peer %s", p)
+	gs.tracer.RemovePeer(p)
 	delete(gs.peers, p)
 	for _, peers := range gs.mesh {
 		delete(peers, p)
@@ -208,6 +214,7 @@ func (gs *GossipSubRouter) handleGraft(p peer.ID, ctl *pb.ControlMessage) []*pb.
 			prune = append(prune, topic)
 		} else {
 			log.Debugf("GRAFT: Add mesh link from %s in %s", p, topic)
+			gs.tracer.Graft(p, topic)
 			peers[p] = struct{}{}
 			gs.tagPeer(p, topic)
 		}
@@ -231,6 +238,7 @@ func (gs *GossipSubRouter) handlePrune(p peer.ID, ctl *pb.ControlMessage) {
 		peers, ok := gs.mesh[topic]
 		if ok {
 			log.Debugf("PRUNE: Remove mesh link to %s in %s", p, topic)
+			gs.tracer.Prune(p, topic)
 			delete(peers, p)
 			gs.untagPeer(p, topic)
 		}
@@ -294,6 +302,7 @@ func (gs *GossipSubRouter) Join(topic string) {
 	}
 
 	log.Debugf("JOIN %s", topic)
+	gs.tracer.Join(topic)
 
 	gmap, ok = gs.fanout[topic]
 	if ok {
@@ -319,6 +328,7 @@ func (gs *GossipSubRouter) Join(topic string) {
 
 	for p := range gmap {
 		log.Debugf("JOIN: Add mesh link to %s in %s", p, topic)
+		gs.tracer.Graft(p, topic)
 		gs.sendGraft(p, topic)
 		gs.tagPeer(p, topic)
 	}
@@ -331,11 +341,13 @@ func (gs *GossipSubRouter) Leave(topic string) {
 	}
 
 	log.Debugf("LEAVE %s", topic)
+	gs.tracer.Leave(topic)
 
 	delete(gs.mesh, topic)
 
 	for p := range gmap {
 		log.Debugf("LEAVE: Remove mesh link to %s in %s", p, topic)
+		gs.tracer.Prune(p, topic)
 		gs.sendPrune(p, topic)
 		gs.untagPeer(p, topic)
 	}
@@ -384,8 +396,10 @@ func (gs *GossipSubRouter) sendRPC(p peer.ID, out *RPC) {
 
 	select {
 	case mch <- out:
+		gs.tracer.SendRPC(out, p)
 	default:
 		log.Infof("dropping message to peer %s: queue full", p)
+		gs.tracer.DropRPC(out, p)
 		// push control messages that need to be retried
 		ctl := out.GetControl()
 		if ctl != nil {
@@ -443,6 +457,7 @@ func (gs *GossipSubRouter) heartbeat() {
 
 			for _, p := range plst {
 				log.Debugf("HEARTBEAT: Add mesh link to %s in %s", p, topic)
+				gs.tracer.Graft(p, topic)
 				peers[p] = struct{}{}
 				gs.tagPeer(p, topic)
 				topics := tograft[p]
@@ -458,6 +473,7 @@ func (gs *GossipSubRouter) heartbeat() {
 
 			for _, p := range plst[:idontneed] {
 				log.Debugf("HEARTBEAT: Remove mesh link to %s in %s", p, topic)
+				gs.tracer.Prune(p, topic)
 				delete(peers, p)
 				gs.untagPeer(p, topic)
 				topics := toprune[p]
diff --git a/pubsub.go b/pubsub.go
index e46f4df..7237259 100644
--- a/pubsub.go
+++ b/pubsub.go
@@ -46,6 +46,8 @@ type PubSub struct {
 
 	disc *discover
 
+	tracer *pubsubTracer
+
 	// size of the outbound message channel that we maintain for each peer
 	peerOutboundQueueSize int
 
@@ -321,6 +323,14 @@ func WithDiscovery(d discovery.Discovery, opts ...DiscoverOpt) Option {
 	}
 }
 
+// WithEventTracer provides a tracer for the pubsub system
+func WithEventTracer(tracer EventTracer) Option {
+	return func(p *PubSub) error {
+		p.tracer = &pubsubTracer{tracer: tracer}
+		return nil
+	}
+}
+
 // processLoop handles all inputs arriving on the channels
 func (p *PubSub) processLoop(ctx context.Context) {
 	defer func() {
@@ -671,6 +681,8 @@ func (p *PubSub) notifyLeave(topic string, pid peer.ID) {
 }
 
 func (p *PubSub) handleIncomingRPC(rpc *RPC) {
+	p.tracer.RecvRPC(rpc)
+
 	for _, subopt := range rpc.GetSubscriptions() {
 		t := subopt.GetTopicid()
 		if subopt.GetSubscribe() {
@@ -724,24 +736,28 @@ func (p *PubSub) pushMsg(msg *Message) {
 	// reject messages from blacklisted peers
 	if p.blacklist.Contains(src) {
 		log.Warningf("dropping message from blacklisted peer %s", src)
+		p.tracer.RejectMessage(msg, "blacklisted peer")
 		return
 	}
 
 	// even if they are forwarded by good peers
 	if p.blacklist.Contains(msg.GetFrom()) {
 		log.Warningf("dropping message from blacklisted source %s", src)
+		p.tracer.RejectMessage(msg, "blacklisted source")
 		return
 	}
 
 	// reject unsigned messages when strict before we even process the id
 	if p.signStrict && msg.Signature == nil {
 		log.Debugf("dropping unsigned message from %s", src)
+		p.tracer.RejectMessage(msg, "missing signature")
 		return
 	}
 
 	// have we already seen and validated this message?
 	id := msgID(msg.Message)
 	if p.seenMessage(id) {
+		p.tracer.DuplicateMessage(msg)
 		return
 	}
 
@@ -755,6 +771,7 @@ func (p *PubSub) pushMsg(msg *Message) {
 }
 
 func (p *PubSub) publishMessage(msg *Message) {
+	p.tracer.DeliverMessage(msg)
 	p.notifySubs(msg)
 	p.rt.Publish(msg.ReceivedFrom, msg.Message)
 }
diff --git a/trace.go b/trace.go
new file mode 100644
index 0000000..08ec219
--- /dev/null
+++ b/trace.go
@@ -0,0 +1,87 @@
+package pubsub
+
+import (
+	"github.com/libp2p/go-libp2p-core/peer"
+	"github.com/libp2p/go-libp2p-core/protocol"
+)
+
+// Generic event tracer interface
+type EventTracer interface {
+	Trace(evt interface{})
+}
+
+type pubsubTracer struct {
+	tracer EventTracer
+}
+
+func (t *pubsubTracer) RejectMessage(msg *Message, reason string) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) DuplicateMessage(msg *Message) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) DeliverMessage(msg *Message) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) AddPeer(p peer.ID, proto protocol.ID) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) RemovePeer(p peer.ID) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) RecvRPC(rpc *RPC) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) SendRPC(rpc *RPC, p peer.ID) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) DropRPC(rpc *RPC, p peer.ID) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) Join(topic string) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) Leave(topic string) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) Graft(p peer.ID, topic string) {
+	if t != nil {
+		// TODO
+	}
+}
+
+func (t *pubsubTracer) Prune(p peer.ID, topic string) {
+	if t != nil {
+		// TODO
+	}
+}
diff --git a/validation.go b/validation.go
index 9253f2a..164bfa9 100644
--- a/validation.go
+++ b/validation.go
@@ -31,6 +31,8 @@ type ValidatorOpt func(addVal *addValReq) error
 type validation struct {
 	p *PubSub
 
+	tracer *pubsubTracer
+
 	// topicVals tracks per topic validators
 	topicVals map[string]*topicVal
 
@@ -90,6 +92,9 @@ func newValidation() *validation {
 // workers
 func (v *validation) Start(p *PubSub) {
 	v.p = p
+	if p.tracer != nil {
+		v.tracer = p.tracer
+	}
 	for i := 0; i < v.validateWorkers; i++ {
 		go v.validateWorker()
 	}
@@ -148,6 +153,7 @@ func (v *validation) Push(src peer.ID, msg *Message) bool {
 		case v.validateQ <- &validateReq{vals, src, msg}:
 		default:
 			log.Warningf("message validation throttled; dropping message from %s", src)
+			v.tracer.RejectMessage(msg, "validation throttled")
 		}
 		return false
 	}
@@ -190,6 +196,7 @@ func (v *validation) validate(vals []*topicVal, src peer.ID, msg *Message) {
 	if msg.Signature != nil {
 		if !v.validateSignature(msg) {
 			log.Warningf("message signature validation failed; dropping message from %s", src)
+			v.tracer.RejectMessage(msg, "invalid signature")
 			return
 		}
 	}
@@ -198,6 +205,7 @@ func (v *validation) validate(vals []*topicVal, src peer.ID, msg *Message) {
 	// and avoid invoking user validators more than once
 	id := msgID(msg.Message)
 	if !v.p.markSeen(id) {
+		v.tracer.DuplicateMessage(msg)
 		return
 	}
 
@@ -214,6 +222,7 @@ func (v *validation) validate(vals []*topicVal, src peer.ID, msg *Message) {
 	for _, val := range inline {
 		if !val.validateMsg(v.p.ctx, src, msg) {
 			log.Debugf("message validation failed; dropping message from %s", src)
+			v.tracer.RejectMessage(msg, "validation failed")
 			return
 		}
 	}
@@ -228,6 +237,7 @@ func (v *validation) validate(vals []*topicVal, src peer.ID, msg *Message) {
 			}()
 		default:
 			log.Warningf("message validation throttled; dropping message from %s", src)
+			v.tracer.RejectMessage(msg, "validation throttled")
 		}
 		return
 	}
@@ -249,6 +259,7 @@ func (v *validation) validateSignature(msg *Message) bool {
 func (v *validation) doValidateTopic(vals []*topicVal, src peer.ID, msg *Message) {
 	if !v.validateTopic(vals, src, msg) {
 		log.Warningf("message validation failed; dropping message from %s", src)
+		v.tracer.RejectMessage(msg, "validation failed")
 		return
 	}
 
@@ -286,6 +297,7 @@ loop:
 	}
 
 	if throttle {
+		v.tracer.RejectMessage(msg, "validation throttled")
 		return false
 	}
 
@@ -310,6 +322,7 @@ func (v *validation) validateSingleTopic(val *topicVal, src peer.ID, msg *Messag
 
 	default:
 		log.Debugf("validation throttled for topic %s", val.topic)
+		v.tracer.RejectMessage(msg, "validation throttled")
 		return false
 	}
 }