diff --git a/accessible/mac/AccessibleWrap.mm b/accessible/mac/AccessibleWrap.mm
index 0d801eefeebc..0e06aa86e913 100644
--- a/accessible/mac/AccessibleWrap.mm
+++ b/accessible/mac/AccessibleWrap.mm
@@ -128,6 +128,18 @@ nsresult AccessibleWrap::HandleAccEvent(AccEvent* aEvent) {
       }
       break;
     }
+    case nsIAccessibleEvent::EVENT_STATE_CHANGE:
+      if (Accessible* accessible = aEvent->GetAccessible()) {
+        accessible->GetNativeInterface((void**)&nativeAcc);
+        if (nativeAcc) {
+          AccStateChangeEvent* event = downcast_accEvent(aEvent);
+          [nativeAcc stateChanged:event->GetState() isEnabled:event->IsStateEnabled()];
+          return NS_OK;
+        } else {
+          return NS_ERROR_FAILURE;
+        }
+      }
+      break;
     default:
       break;
   }
diff --git a/accessible/mac/Platform.mm b/accessible/mac/Platform.mm
index 14c1303f2778..2074c4c8537f 100644
--- a/accessible/mac/Platform.mm
+++ b/accessible/mac/Platform.mm
@@ -131,8 +131,11 @@ void ProxyEvent(ProxyAccessible* aProxy, uint32_t aEventType) {
   }
 }
 
-void ProxyStateChangeEvent(ProxyAccessible* aProxy, uint64_t, bool) {
-  // mac doesn't care about state change events
+void ProxyStateChangeEvent(ProxyAccessible* aProxy, uint64_t aState, bool aEnabled) {
+  mozAccessible* wrapper = GetNativeFromProxy(aProxy);
+  if (wrapper) {
+    [wrapper stateChanged:aState isEnabled:aEnabled];
+  }
 }
 
 void ProxyCaretMoveEvent(ProxyAccessible* aTarget, int32_t aOffset) {
diff --git a/accessible/mac/mozAccessible.h b/accessible/mac/mozAccessible.h
index 46eedfb5c517..d68425fe209b 100644
--- a/accessible/mac/mozAccessible.h
+++ b/accessible/mac/mozAccessible.h
@@ -62,6 +62,11 @@ static const uintptr_t IS_PROXY = 1;
    * The role of our gecko accessible.
    */
   mozilla::a11y::role mRole;
+
+  /**
+   * A cache of a subset of our states.
+   */
+  uint64_t mCachedState;
 }
 
 // return the Accessible for this mozAccessible if it exists.
@@ -135,6 +140,12 @@ static const uintptr_t IS_PROXY = 1;
 // Get gecko accessible's state filtered through given mask.
 - (uint64_t)stateWithMask:(uint64_t)mask;
 
+// Notify of a state change, so the cache can be altered.
+- (void)stateChanged:(uint64_t)state isEnabled:(BOOL)enabled;
+
+// Invalidate cached state.
+- (void)invalidateState;
+
 #pragma mark -
 
 // invalidates and removes all our children from our cached array.
diff --git a/accessible/mac/mozAccessible.mm b/accessible/mac/mozAccessible.mm
index 8cd56b6982bd..e8d12525b95f 100644
--- a/accessible/mac/mozAccessible.mm
+++ b/accessible/mac/mozAccessible.mm
@@ -245,22 +245,57 @@ static inline NSMutableArray* ConvertToNSArray(nsTArray<ProxyAccessible*>& aArra
   NS_OBJC_END_TRY_ABORT_BLOCK_NIL;
 }
 
+static const uint64_t kCachedStates =
+    states::CHECKED states::PRESSED | states::MIXED | states::EXPANDED;
+static const uint64_t kCacheInitialized = ((uint64_t)0x1) << 63;
+
 - (uint64_t)state {
+  uint64_t state = 0;
   if (AccessibleWrap* accWrap = [self getGeckoAccessible]) {
-    return accWrap->State();
+    state = accWrap->State();
   }
 
   if (ProxyAccessible* proxy = [self getProxyAccessible]) {
-    return proxy->State();
+    state = proxy->State();
   }
 
-  return 0;
+  if (!(mCachedState & kCacheInitialized)) {
+    mCachedState = state & kCachedStates;
+    mCachedState |= kCacheInitialized;
+  }
+
+  return state;
 }
 
 - (uint64_t)stateWithMask:(uint64_t)mask {
+  if ((mask & kCachedStates) == mask && (mCachedState & kCacheInitialized) != 0) {
+    return mCachedState & mask;
+  }
+
   return [self state] & mask;
 }
 
+- (void)stateChanged:(uint64_t)state isEnabled:(BOOL)enabled {
+  if ((state & kCachedStates) == 0) {
+    return;
+  }
+
+  if (!(mCachedState & kCacheInitialized)) {
+    [self state];
+    return;
+  }
+
+  if (enabled) {
+    mCachedState |= state;
+  } else {
+    mCachedState &= ~state;
+  }
+}
+
+- (void)invalidateState {
+  mCachedState = 0;
+}
+
 - (id)accessibilityAttributeValue:(NSString*)attribute {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL;
 
@@ -622,6 +657,8 @@ static inline NSMutableArray* ConvertToNSArray(nsTArray<ProxyAccessible*>& aArra
     } else if (proxy) {
       proxy->DoAction(0);
     }
+    // Activating accessible may alter its state.
+    [self invalidateState];
   }
 }
 
@@ -1248,6 +1285,8 @@ struct RoleDescrComparator {
 
   [self invalidateChildren];
 
+  [self invalidateState];
+
   mGeckoAccessible = 0;
 
   [self postNotification:NSAccessibilityUIElementDestroyedNotification];