diff --git a/event/capabilities.d.ts b/event/capabilities.d.ts
index 37848575..2d95cd50 100644
--- a/event/capabilities.d.ts
+++ b/event/capabilities.d.ts
@@ -16,6 +16,8 @@ export interface RoomFeatures {
 	 * If a message type isn't listed here, it should be treated as support level -2 (will be rejected).
 	 */
 	file?: Record<CapabilityMsgType, FileFeatures>
+	state?: Record<EventType, StateFeatures>
+	member_actions?: Record<MemberAction, CapabilitySupportLevel>
 
 	/** Maximum length of normal text messages. */
 	max_text_length?: integer
@@ -72,6 +74,21 @@ declare type MIMETypeOrPattern =
 	| `${MIMEClass}/${string}`
 	| `${MIMEClass}/${string}; ${string}`
 
+export enum MemberAction {
+	Ban = "ban",
+	Kick = "kick",
+	Leave = "leave",
+	RevokeInvite = "revoke_invite",
+	Invite = "invite",
+}
+
+declare type EventType = string
+
+// This is an object for future extensibility (e.g. max name/topic length)
+export interface StateFeatures {
+	level: CapabilitySupportLevel
+}
+
 export enum CapabilityMsgType {
 	// Real message types used in the `msgtype` field
 	Image = "m.image",
diff --git a/event/capabilities.go b/event/capabilities.go
index 42afe5b6..5ecea4a2 100644
--- a/event/capabilities.go
+++ b/event/capabilities.go
@@ -28,8 +28,10 @@ type RoomFeatures struct {
 
 	// N.B. New fields need to be added to the Hash function to be included in the deduplication hash.
 
-	Formatting FormattingFeatureMap `json:"formatting,omitempty"`
-	File       FileFeatureMap       `json:"file,omitempty"`
+	Formatting    FormattingFeatureMap `json:"formatting,omitempty"`
+	File          FileFeatureMap       `json:"file,omitempty"`
+	State         StateFeatureMap      `json:"state,omitempty"`
+	MemberActions MemberFeatureMap     `json:"member_actions,omitempty"`
 
 	MaxTextLength int `json:"max_text_length,omitempty"`
 
@@ -74,6 +76,8 @@ func (rf *RoomFeatures) Clone() *RoomFeatures {
 	clone := *rf
 	clone.File = clone.File.Clone()
 	clone.Formatting = maps.Clone(clone.Formatting)
+	clone.State = clone.State.Clone()
+	clone.MemberActions = clone.MemberActions.Clone()
 	clone.EditMaxAge = ptr.Clone(clone.EditMaxAge)
 	clone.DeleteMaxAge = ptr.Clone(clone.DeleteMaxAge)
 	clone.DisappearingTimer = clone.DisappearingTimer.Clone()
@@ -81,6 +85,48 @@ func (rf *RoomFeatures) Clone() *RoomFeatures {
 	return &clone
 }
 
+type MemberFeatureMap map[MemberAction]CapabilitySupportLevel
+
+func (mfm MemberFeatureMap) Clone() MemberFeatureMap {
+	return maps.Clone(mfm)
+}
+
+type MemberAction string
+
+const (
+	MemberActionBan          MemberAction = "ban"
+	MemberActionKick         MemberAction = "kick"
+	MemberActionLeave        MemberAction = "leave"
+	MemberActionRevokeInvite MemberAction = "revoke_invite"
+	MemberActionInvite       MemberAction = "invite"
+)
+
+type StateFeatureMap map[string]*StateFeatures
+
+func (sfm StateFeatureMap) Clone() StateFeatureMap {
+	dup := maps.Clone(sfm)
+	for key, value := range dup {
+		dup[key] = value.Clone()
+	}
+	return dup
+}
+
+type StateFeatures struct {
+	Level CapabilitySupportLevel `json:"level"`
+}
+
+func (sf *StateFeatures) Clone() *StateFeatures {
+	if sf == nil {
+		return nil
+	}
+	clone := *sf
+	return &clone
+}
+
+func (sf *StateFeatures) Hash() []byte {
+	return sf.Level.Hash()
+}
+
 type FormattingFeatureMap map[FormattingFeature]CapabilitySupportLevel
 
 type FileFeatureMap map[CapabilityMsgType]*FileFeatures
@@ -266,6 +312,8 @@ func (rf *RoomFeatures) Hash() []byte {
 
 	hashMap(hasher, "formatting", rf.Formatting)
 	hashMap(hasher, "file", rf.File)
+	hashMap(hasher, "state", rf.State)
+	hashMap(hasher, "member_actions", rf.MemberActions)
 
 	hashInt(hasher, "max_text_length", rf.MaxTextLength)