diff --git a/React/Base/RCTBridgeModule.h b/React/Base/RCTBridgeModule.h
index 3e31621d0c..1ab00bb5cf 100644
--- a/React/Base/RCTBridgeModule.h
+++ b/React/Base/RCTBridgeModule.h
@@ -263,6 +263,19 @@ RCT_EXTERN void RCTRegisterModule(Class); \
     return &config; \
   }
 
+/**
+ * Most modules can be used from any thread. All of the modules exported non-sync method will be called on its
+ * methodQueue, and the module will be constructed lazily when its first invoked. Some modules have main need to access
+ * information that's main queue only (e.g. most UIKit classes). Since we don't want to dispatch synchronously to the
+ * main thread to this safely, we construct these moduels and export their constants ahead-of-time.
+ *
+ * Note that when set to false, the module constructor will be called from any thread.
+ *
+ * This requirement is currently inferred by checking if the module has a custom initializer or if there's exported
+ * constants. In the future, we'll stop automatically inferring this and instead only rely on this method.
+ */
++ (BOOL)requiresMainQueueSetup;
+
 /**
  * Injects methods into JS.  Entries in this array are used in addition to any
  * methods defined using the macros above.  This method is called only once,
@@ -271,13 +284,15 @@ RCT_EXTERN void RCTRegisterModule(Class); \
 - (NSArray<id<RCTBridgeMethod>> *)methodsToExport;
 
 /**
- * Injects constants into JS. These constants are made accessible via
- * NativeModules.ModuleName.X.  It is only called once for the lifetime of the
- * bridge, so it is not suitable for returning dynamic values, but may be used
- * for long-lived values such as session keys, that are regenerated only as
- * part of a reload of the entire React application.
+ * Injects constants into JS. These constants are made accessible via NativeModules.ModuleName.X. It is only called once
+ * for the lifetime of the bridge, so it is not suitable for returning dynamic values, but may be used for long-lived
+ * values such as session keys, that are regenerated only as part of a reload of the entire React application.
+ *
+ * If you implement this method and do not implement `requiresMainThreadSetup`, you will trigger deprecated logic
+ * that eagerly initializes your module on bridge startup. In the future, this behaviour will be changed to default
+ * to initializing lazily, and even modules with constants will be initialized lazily.
  */
-- (NSDictionary<NSString *, id> *)constantsToExport;
+- (NSDictionary *)constantsToExport;
 
 /**
  * Notifies the module that a batch of JS method invocations has just completed.
diff --git a/React/Base/RCTModuleData.mm b/React/Base/RCTModuleData.mm
index ae728a2c55..c1645549b3 100644
--- a/React/Base/RCTModuleData.mm
+++ b/React/Base/RCTModuleData.mm
@@ -38,21 +38,37 @@
   _implementsBatchDidComplete = [_moduleClass instancesRespondToSelector:@selector(batchDidComplete)];
   _implementsPartialBatchDidFlush = [_moduleClass instancesRespondToSelector:@selector(partialBatchDidFlush)];
 
-  static IMP objectInitMethod;
-  static dispatch_once_t onceToken;
-  dispatch_once(&onceToken, ^{
-    objectInitMethod = [NSObject instanceMethodForSelector:@selector(init)];
-  });
-
-  // If a module overrides `constantsToExport` then we must assume that it
-  // must be called on the main thread, because it may need to access UIKit.
+  // If a module overrides `constantsToExport` and doesn't implement `requiresMainQueueSetup`, then we must assume
+  // that it must be called on the main thread, because it may need to access UIKit.
   _hasConstantsToExport = [_moduleClass instancesRespondToSelector:@selector(constantsToExport)];
 
-  // If a module overrides `init` then we must assume that it expects to be
-  // initialized on the main thread, because it may need to access UIKit.
-  const BOOL hasCustomInit = !_instance && [_moduleClass instanceMethodForSelector:@selector(init)] != objectInitMethod;
+  const BOOL implementsRequireMainQueueSetup = [_moduleClass respondsToSelector:@selector(requiresMainQueueSetup)];
+  if (implementsRequireMainQueueSetup) {
+    _requiresMainQueueSetup = [_moduleClass requiresMainQueueSetup];
+  } else {
+    static IMP objectInitMethod;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+      objectInitMethod = [NSObject instanceMethodForSelector:@selector(init)];
+    });
 
-  _requiresMainQueueSetup = _hasConstantsToExport || hasCustomInit;
+    // If a module overrides `init` then we must assume that it expects to be
+    // initialized on the main thread, because it may need to access UIKit.
+    const BOOL hasCustomInit = !_instance && [_moduleClass instanceMethodForSelector:@selector(init)] != objectInitMethod;
+
+    _requiresMainQueueSetup = _hasConstantsToExport || hasCustomInit;
+    if (_requiresMainQueueSetup) {
+      const char *methodName = "";
+      if (_hasConstantsToExport) {
+        methodName = "constantsToExport";
+      } else if (hasCustomInit) {
+        methodName = "init";
+      }
+      RCTLogWarn(@"Module %@ requires main queue setup since it overrides `%s` but doesn't implement "
+        "`requiresMainQueueSetup. In a future release React Native will default to initializing all native modules "
+        "on a background thread unless explicitly opted-out of.", _moduleClass, methodName);
+    }
+  }
 }
 
 - (instancetype)initWithModuleClass:(Class)moduleClass
@@ -291,9 +307,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init);
   if (_hasConstantsToExport && !_constantsToExport) {
     RCT_PROFILE_BEGIN_EVENT(RCTProfileTagAlways, ([NSString stringWithFormat:@"[RCTModuleData gatherConstants] %@", _moduleClass]), nil);
     (void)[self instance];
-    if (!_requiresMainQueueSetup) {
-      _constantsToExport = [_instance constantsToExport] ?: @{};
-    } else {
+    if (_requiresMainQueueSetup) {
       if (!RCTIsMainQueue()) {
         RCTLogWarn(@"Required dispatch_sync to load constants for %@. This may lead to deadlocks", _moduleClass);
       }
@@ -301,6 +315,8 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init);
       RCTUnsafeExecuteOnMainQueueSync(^{
         self->_constantsToExport = [self->_instance constantsToExport] ?: @{};
       });
+    } else {
+      _constantsToExport = [_instance constantsToExport] ?: @{};
     }
     RCT_PROFILE_END_EVENT(RCTProfileTagAlways, @"");
   }
diff --git a/React/CxxModule/RCTCxxModule.mm b/React/CxxModule/RCTCxxModule.mm
index 3838cb7bcc..295aac82c2 100644
--- a/React/CxxModule/RCTCxxModule.mm
+++ b/React/CxxModule/RCTCxxModule.mm
@@ -28,6 +28,11 @@ using namespace facebook::react;
   return @"";
 }
 
++ (BOOL)requiresMainQueueSetup
+{
+  return NO;
+}
+
 - (void)lazyInit
 {
   if (!_module) {