diff --git a/clientapi/routing/createroom.go b/clientapi/routing/createroom.go
index 964200760..8f63df48e 100644
--- a/clientapi/routing/createroom.go
+++ b/clientapi/routing/createroom.go
@@ -299,7 +299,7 @@ func createRoom(
 			builder.PrevEvents = []gomatrixserverlib.EventReference{builtEvents[i-1].EventReference()}
 		}
 		var ev *gomatrixserverlib.Event
-		ev, err = buildEvent(&builder, &authEvents, cfg, evTime)
+		ev, err = buildEvent(&builder, &authEvents, cfg, evTime, roomVersion)
 		if err != nil {
 			util.GetLogger(req.Context()).WithError(err).Error("buildEvent failed")
 			return jsonerror.InternalServerError()
@@ -368,6 +368,7 @@ func buildEvent(
 	provider gomatrixserverlib.AuthEventProvider,
 	cfg *config.Dendrite,
 	evTime time.Time,
+	roomVersion gomatrixserverlib.RoomVersion,
 ) (*gomatrixserverlib.Event, error) {
 	eventsNeeded, err := gomatrixserverlib.StateNeededForEventBuilder(builder)
 	if err != nil {
@@ -379,7 +380,10 @@ func buildEvent(
 	}
 	builder.AuthEvents = refs
 	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
-	event, err := builder.Build(eventID, evTime, cfg.Matrix.ServerName, cfg.Matrix.KeyID, cfg.Matrix.PrivateKey)
+	event, err := builder.Build(
+		eventID, evTime, cfg.Matrix.ServerName, cfg.Matrix.KeyID,
+		cfg.Matrix.PrivateKey, roomVersion,
+	)
 	if err != nil {
 		return nil, fmt.Errorf("cannot build event %s : Builder failed to build. %w", builder.Type, err)
 	}
diff --git a/clientapi/routing/joinroom.go b/clientapi/routing/joinroom.go
index 7643c41f3..33ceda5d0 100644
--- a/clientapi/routing/joinroom.go
+++ b/clientapi/routing/joinroom.go
@@ -27,6 +27,7 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/producers"
 	"github.com/matrix-org/dendrite/common"
 	"github.com/matrix-org/dendrite/common/config"
+	"github.com/matrix-org/dendrite/roomserver/api"
 	roomserverAPI "github.com/matrix-org/dendrite/roomserver/api"
 	"github.com/matrix-org/gomatrix"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -299,7 +300,19 @@ func (r joinRoomReq) joinRoomUsingServers(
 // server was invalid this returns an error.
 // Otherwise this returns a JSONResponse.
 func (r joinRoomReq) joinRoomUsingServer(roomID string, server gomatrixserverlib.ServerName) (*util.JSONResponse, error) {
-	respMakeJoin, err := r.federation.MakeJoin(r.req.Context(), server, roomID, r.userID, []int{1})
+	// Ask the room server for information about room versions.
+	var request api.QueryRoomVersionCapabilitiesRequest
+	var response api.QueryRoomVersionCapabilitiesResponse
+	if err := r.queryAPI.QueryRoomVersionCapabilities(r.req.Context(), &request, &response); err != nil {
+		return nil, err
+	}
+	var supportedVersions []gomatrixserverlib.RoomVersion
+	for version, descriptor := range response.AvailableRoomVersions {
+		if descriptor == "stable" {
+			supportedVersions = append(supportedVersions, version)
+		}
+	}
+	respMakeJoin, err := r.federation.MakeJoin(r.req.Context(), server, roomID, r.userID, supportedVersions)
 	if err != nil {
 		// TODO: Check if the user was not allowed to join the room.
 		return nil, err
@@ -312,9 +325,22 @@ func (r joinRoomReq) joinRoomUsingServer(roomID string, server gomatrixserverlib
 		return nil, err
 	}
 
+	if respMakeJoin.RoomVersion == "" {
+		respMakeJoin.RoomVersion = gomatrixserverlib.RoomVersionV1
+	}
+	if _, err := respMakeJoin.RoomVersion.EventFormat(); err != nil {
+		return &util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.UnsupportedRoomVersion(
+				fmt.Sprintf("Room version '%s' is not supported", respMakeJoin.RoomVersion),
+			),
+		}, nil
+	}
+
 	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), r.cfg.Matrix.ServerName)
 	event, err := respMakeJoin.JoinEvent.Build(
-		eventID, r.evTime, r.cfg.Matrix.ServerName, r.cfg.Matrix.KeyID, r.cfg.Matrix.PrivateKey,
+		eventID, r.evTime, r.cfg.Matrix.ServerName, r.cfg.Matrix.KeyID,
+		r.cfg.Matrix.PrivateKey, respMakeJoin.RoomVersion,
 	)
 	if err != nil {
 		util.GetLogger(r.req.Context()).WithError(err).Error("respMakeJoin.JoinEvent.Build failed")
diff --git a/cmd/create-room-events/main.go b/cmd/create-room-events/main.go
index ef442a0c4..623890ba3 100644
--- a/cmd/create-room-events/main.go
+++ b/cmd/create-room-events/main.go
@@ -108,7 +108,10 @@ func buildAndOutput() gomatrixserverlib.EventReference {
 	name := gomatrixserverlib.ServerName(*serverName)
 	key := gomatrixserverlib.KeyID(*keyID)
 
-	event, err := b.Build(id, now, name, key, privateKey)
+	event, err := b.Build(
+		id, now, name, key, privateKey,
+		gomatrixserverlib.RoomVersionV1,
+	)
 	if err != nil {
 		panic(err)
 	}
@@ -127,7 +130,7 @@ func writeEvent(event gomatrixserverlib.Event) {
 		ire.Kind = api.KindNew
 		ire.Event = event.Headered(gomatrixserverlib.RoomVersionV1)
 		authEventIDs := []string{}
-		for _, ref := range b.AuthEvents {
+		for _, ref := range b.AuthEvents.([]gomatrixserverlib.EventReference) {
 			authEventIDs = append(authEventIDs, ref.EventID)
 		}
 		ire.AuthEventIDs = authEventIDs
diff --git a/common/events.go b/common/events.go
index ff46e8e0b..5d8ac90df 100644
--- a/common/events.go
+++ b/common/events.go
@@ -48,7 +48,10 @@ func BuildEvent(
 	}
 
 	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
-	event, err := builder.Build(eventID, evTime, cfg.Matrix.ServerName, cfg.Matrix.KeyID, cfg.Matrix.PrivateKey)
+	event, err := builder.Build(
+		eventID, evTime, cfg.Matrix.ServerName, cfg.Matrix.KeyID,
+		cfg.Matrix.PrivateKey, queryRes.RoomVersion,
+	)
 	if err != nil {
 		return nil, err
 	}
@@ -73,7 +76,7 @@ func AddPrevEventsToEvent(
 		StateToFetch: eventsNeeded.Tuples(),
 	}
 	if queryRes == nil {
-		queryRes = &api.QueryLatestEventsAndStateResponse{}
+		*queryRes = api.QueryLatestEventsAndStateResponse{}
 	}
 	if err = queryAPI.QueryLatestEventsAndState(ctx, &queryReq, queryRes); err != nil {
 		return err
diff --git a/federationapi/routing/invite.go b/federationapi/routing/invite.go
index 946103462..9713b7229 100644
--- a/federationapi/routing/invite.go
+++ b/federationapi/routing/invite.go
@@ -70,9 +70,10 @@ func Invite(
 	}
 
 	// Check that the event is signed by the server sending the request.
+	redacted := event.Redact()
 	verifyRequests := []gomatrixserverlib.VerifyJSONRequest{{
 		ServerName: event.Origin(),
-		Message:    event.Redact().JSON(),
+		Message:    redacted.JSON(),
 		AtTS:       event.OriginServerTS(),
 	}}
 	verifyResults, err := keys.VerifyJSONs(httpReq.Context(), verifyRequests)
diff --git a/federationapi/routing/join.go b/federationapi/routing/join.go
index 7d48c86dc..aebd695a0 100644
--- a/federationapi/routing/join.go
+++ b/federationapi/routing/join.go
@@ -137,9 +137,10 @@ func SendJoin(
 	}
 
 	// Check that the event is signed by the server sending the request.
+	redacted := event.Redact()
 	verifyRequests := []gomatrixserverlib.VerifyJSONRequest{{
 		ServerName: event.Origin(),
-		Message:    event.Redact().JSON(),
+		Message:    redacted.JSON(),
 		AtTS:       event.OriginServerTS(),
 	}}
 	verifyResults, err := keys.VerifyJSONs(httpReq.Context(), verifyRequests)
diff --git a/federationapi/routing/leave.go b/federationapi/routing/leave.go
index 3eceb6f25..00d71866d 100644
--- a/federationapi/routing/leave.go
+++ b/federationapi/routing/leave.go
@@ -134,9 +134,10 @@ func SendLeave(
 	}
 
 	// Check that the event is signed by the server sending the request.
+	redacted := event.Redact()
 	verifyRequests := []gomatrixserverlib.VerifyJSONRequest{{
 		ServerName: event.Origin(),
-		Message:    event.Redact().JSON(),
+		Message:    redacted.JSON(),
 		AtTS:       event.OriginServerTS(),
 	}}
 	verifyResults, err := keys.VerifyJSONs(httpReq.Context(), verifyRequests)
diff --git a/federationapi/routing/threepid.go b/federationapi/routing/threepid.go
index 18ebc07e1..b86fd58d8 100644
--- a/federationapi/routing/threepid.go
+++ b/federationapi/routing/threepid.go
@@ -282,7 +282,8 @@ func buildMembershipEvent(
 
 	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
 	event, err := builder.Build(
-		eventID, time.Now(), cfg.Matrix.ServerName, cfg.Matrix.KeyID, cfg.Matrix.PrivateKey,
+		eventID, time.Now(), cfg.Matrix.ServerName, cfg.Matrix.KeyID,
+		cfg.Matrix.PrivateKey, queryRes.RoomVersion,
 	)
 
 	return &event, err
diff --git a/go.mod b/go.mod
index 3ceaea528..e6591d572 100644
--- a/go.mod
+++ b/go.mod
@@ -11,7 +11,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200318135427-31631a9ef51f
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200304164012-aa524245b658
 	github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20200318180716-bc4ff56961e2
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20200319170723-77824b449610
 	github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1
 	github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7
 	github.com/mattn/go-sqlite3 v2.0.2+incompatible
diff --git a/go.sum b/go.sum
index 0f4542b28..658c3160b 100644
--- a/go.sum
+++ b/go.sum
@@ -276,6 +276,10 @@ github.com/matrix-org/gomatrixserverlib v0.0.0-20200318145320-bc896516d72a h1:7+
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200318145320-bc896516d72a/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200318150006-bc27294f9203 h1:7HkL6bF7/M2cYteNFVtvGW5qjD4wHIiR0HsdCm2Rqao=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200318150006-bc27294f9203/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200318180716-bc4ff56961e2 h1:y4DOMbhgPAnATHJ4lNxTWxIlJG0SlIPhvukx1sQkty4=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200318180716-bc4ff56961e2/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200319170723-77824b449610 h1:g63T0TphmjOJh3sZFwX1YdJH4SQWXOlGn++xr8MbB+E=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200319170723-77824b449610/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1 h1:osLoFdOy+ChQqVUn2PeTDETFftVkl4w9t/OW18g3lnk=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1/go.mod h1:cXoYQIENbdWIQHt1SyCo6Bl3C3raHwJ0wgVrXHSqf+A=
 github.com/matrix-org/util v0.0.0-20171127121716-2e2df66af2f5 h1:W7l5CP4V7wPyPb4tYE11dbmeAOwtFQBTW0rf4OonOS8=
@@ -470,6 +474,8 @@ go.uber.org/atomic v1.3.0 h1:vs7fgriifsPbGdK3bNuMWapNn3qnZhCRXc19NRdq010=
 go.uber.org/atomic v1.3.0/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
 go.uber.org/atomic v1.4.0 h1:cxzIVoETapQEqDhQu3QfnvXAV4AlzcvUCxkVUFw3+EU=
 go.uber.org/atomic v1.4.0/go.mod h1:gD2HeocX3+yG+ygLZcrzQJaqmWj9AIm7n08wl/qW/PE=
+go.uber.org/atomic v1.6.0 h1:Ezj3JGmsOnG1MoRWQkPBsKLe9DwWD9QeXzTRzzldNVk=
+go.uber.org/atomic v1.6.0/go.mod h1:sABNBOSYdrvTF6hTgEIbc7YasKWGhgEQZyfxyTvoXHQ=
 go.uber.org/multierr v1.1.0/go.mod h1:wR5kodmAFQ0UK8QlbwjlSNy0Z68gJhDJUG5sjR94q/0=
 go.uber.org/zap v1.10.0/go.mod h1:vwi/ZaCAaUcBkycHslxD9B2zi4UTXhF60s6SWpuDF0Q=
 golang.org/x/crypto v0.0.0-20170930174604-9419663f5a44/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
@@ -491,6 +497,7 @@ golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/lint v0.0.0-20190227174305-5b3e6a55c961/go.mod h1:wehouNa3lNwaWXcvxsM5YxQ5yQlVC4a0KAMCusXpPoU=
 golang.org/x/lint v0.0.0-20190313153728-d0100b6bd8b3/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
+golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
 golang.org/x/mod v0.0.0-20190513183733-4bf6d317e70e/go.mod h1:mXi4GBBbnImb6dmsKGUJ2LatrhH/nqhxcFungHvyanc=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -559,6 +566,7 @@ golang.org/x/tools v0.0.0-20190910044552-dd2b5c81c578/go.mod h1:b+2E5dAYhXwXZwtn
 golang.org/x/tools v0.0.0-20190911230505-6bfd74cf029c/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20190912215617-3720d1ec3678 h1:rM1Udd0CgtYI3KUIhu9ROz0QCqjW+n/ODp/hH7c60Xc=
 golang.org/x/tools v0.0.0-20190912215617-3720d1ec3678/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20191029041327-9cc4af7d6b2c/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
diff --git a/roomserver/alias/alias.go b/roomserver/alias/alias.go
index dfb7e76a7..fa401f504 100644
--- a/roomserver/alias/alias.go
+++ b/roomserver/alias/alias.go
@@ -253,7 +253,8 @@ func (r *RoomserverAliasAPI) sendUpdatedAliasesEvent(
 	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), r.Cfg.Matrix.ServerName)
 	now := time.Now()
 	event, err := builder.Build(
-		eventID, now, r.Cfg.Matrix.ServerName, r.Cfg.Matrix.KeyID, r.Cfg.Matrix.PrivateKey,
+		eventID, now, r.Cfg.Matrix.ServerName, r.Cfg.Matrix.KeyID,
+		r.Cfg.Matrix.PrivateKey, roomVersion,
 	)
 	if err != nil {
 		return err
diff --git a/roomserver/query/query.go b/roomserver/query/query.go
index 2638919ad..f2e9e6155 100644
--- a/roomserver/query/query.go
+++ b/roomserver/query/query.go
@@ -123,6 +123,7 @@ func (r *RoomserverQueryAPI) QueryLatestEventsAndState(
 		return nil
 	}
 	response.RoomExists = true
+	response.RoomVersion = roomVersion
 
 	var currentStateSnapshotNID types.StateSnapshotNID
 	response.LatestEvents, currentStateSnapshotNID, response.Depth, err =
@@ -174,6 +175,7 @@ func (r *RoomserverQueryAPI) QueryStateAfterEvents(
 		return nil
 	}
 	response.RoomExists = true
+	response.RoomVersion = roomVersion
 
 	prevStates, err := r.DB.StateAtEventIDs(ctx, request.PrevEventIDs)
 	if err != nil {
diff --git a/roomserver/query/query_test.go b/roomserver/query/query_test.go
index 76c2e158f..7e040c6fb 100644
--- a/roomserver/query/query_test.go
+++ b/roomserver/query/query_test.go
@@ -54,7 +54,9 @@ func (db *getEventDB) addFakeEvent(eventID string, authIDs []string) error {
 		return err
 	}
 
-	event, err := gomatrixserverlib.NewEventFromTrustedJSON(eventJSON, false)
+	event, err := gomatrixserverlib.NewEventFromTrustedJSON(
+		eventJSON, false, gomatrixserverlib.RoomVersionV1,
+	)
 	if err != nil {
 		return err
 	}
diff --git a/roomserver/storage/postgres/storage.go b/roomserver/storage/postgres/storage.go
index 084b83ce6..3bed09477 100644
--- a/roomserver/storage/postgres/storage.go
+++ b/roomserver/storage/postgres/storage.go
@@ -257,7 +257,10 @@ func (d *Database) Events(
 		result := &results[i]
 		result.EventNID = eventJSON.EventNID
 		// TODO: Use NewEventFromTrustedJSON for efficiency
-		result.Event, err = gomatrixserverlib.NewEventFromUntrustedJSON(eventJSON.EventJSON)
+		// TODO: Room version here
+		result.Event, err = gomatrixserverlib.NewEventFromUntrustedJSON(
+			eventJSON.EventJSON, gomatrixserverlib.RoomVersionV1,
+		)
 		if err != nil {
 			return nil, err
 		}
diff --git a/roomserver/storage/sqlite3/storage.go b/roomserver/storage/sqlite3/storage.go
index 28d608ca5..70fd979d6 100644
--- a/roomserver/storage/sqlite3/storage.go
+++ b/roomserver/storage/sqlite3/storage.go
@@ -310,7 +310,10 @@ func (d *Database) Events(
 			result := &results[i]
 			result.EventNID = eventJSON.EventNID
 			// TODO: Use NewEventFromTrustedJSON for efficiency
-			result.Event, err = gomatrixserverlib.NewEventFromUntrustedJSON(eventJSON.EventJSON)
+			// TODO: Room version here
+			result.Event, err = gomatrixserverlib.NewEventFromUntrustedJSON(
+				eventJSON.EventJSON, gomatrixserverlib.RoomVersionV1,
+			)
 			if err != nil {
 				return nil
 			}
diff --git a/roomserver/version/version.go b/roomserver/version/version.go
index b18df49f5..ed16ecca0 100644
--- a/roomserver/version/version.go
+++ b/roomserver/version/version.go
@@ -39,8 +39,8 @@ var roomVersions = map[gomatrixserverlib.RoomVersion]RoomVersionDescription{
 		Stable:    true,
 	},
 	gomatrixserverlib.RoomVersionV2: RoomVersionDescription{
-		Supported: false,
-		Stable:    false,
+		Supported: true,
+		Stable:    true,
 	},
 	gomatrixserverlib.RoomVersionV3: RoomVersionDescription{
 		Supported: false,
@@ -59,7 +59,7 @@ var roomVersions = map[gomatrixserverlib.RoomVersion]RoomVersionDescription{
 // DefaultRoomVersion contains the room version that will, by
 // default, be used to create new rooms on this server.
 func DefaultRoomVersion() gomatrixserverlib.RoomVersion {
-	return gomatrixserverlib.RoomVersionV1
+	return gomatrixserverlib.RoomVersionV2
 }
 
 // RoomVersions returns a map of all known room versions to this