diff --git a/src/api/become-observed.ts b/src/api/become-observed.ts
index 1646991dc..8573b01a0 100644
--- a/src/api/become-observed.ts
+++ b/src/api/become-observed.ts
@@ -5,11 +5,17 @@ import {
     Lambda,
     ObservableMap,
     fail,
-    getAtom
+    getAtom,
+    ObservableSet
 } from "../internal"
 
 export function onBecomeObserved(
-    value: IObservable | IComputedValue<any> | IObservableArray<any> | ObservableMap<any, any>,
+    value:
+        | IObservable
+        | IComputedValue<any>
+        | IObservableArray<any>
+        | ObservableMap<any, any>
+        | ObservableSet<any>,
     listener: Lambda
 ): Lambda
 export function onBecomeObserved<K, V = any>(
@@ -22,7 +28,12 @@ export function onBecomeObserved(thing, arg2, arg3?): Lambda {
 }
 
 export function onBecomeUnobserved(
-    value: IObservable | IComputedValue<any> | IObservableArray<any> | ObservableMap<any, any>,
+    value:
+        | IObservable
+        | IComputedValue<any>
+        | IObservableArray<any>
+        | ObservableMap<any, any>
+        | ObservableSet<any>,
     listener: Lambda
 ): Lambda
 export function onBecomeUnobserved<K, V = any>(
diff --git a/src/api/intercept-read.ts b/src/api/intercept-read.ts
index d8be9d88f..72c33dee8 100644
--- a/src/api/intercept-read.ts
+++ b/src/api/intercept-read.ts
@@ -8,7 +8,8 @@ import {
     isObservableArray,
     isObservableMap,
     isObservableObject,
-    isObservableValue
+    isObservableValue,
+    ObservableSet
 } from "../internal"
 
 export type ReadInterceptor<T> = (value: any) => T
@@ -23,6 +24,10 @@ export function interceptReads<K, V>(
     observableMap: ObservableMap<K, V>,
     handler: ReadInterceptor<V>
 ): Lambda
+export function interceptReads<V>(
+    observableSet: ObservableSet<V>,
+    handler: ReadInterceptor<V>
+): Lambda
 export function interceptReads(
     object: Object,
     property: string,
diff --git a/src/api/intercept.ts b/src/api/intercept.ts
index b0835785a..8775b4584 100644
--- a/src/api/intercept.ts
+++ b/src/api/intercept.ts
@@ -9,7 +9,9 @@ import {
     IValueWillChange,
     Lambda,
     ObservableMap,
-    getAdministration
+    getAdministration,
+    ObservableSet,
+    ISetWillChange
 } from "../internal"
 
 export function intercept<T>(
@@ -24,6 +26,10 @@ export function intercept<K, V>(
     observableMap: ObservableMap<K, V>,
     handler: IInterceptor<IMapWillChange<K, V>>
 ): Lambda
+export function intercept<V>(
+    observableMap: ObservableSet<V>,
+    handler: IInterceptor<ISetWillChange<V>>
+): Lambda
 export function intercept<K, V>(
     observableMap: ObservableMap<K, V>,
     property: K,
diff --git a/src/api/observable.ts b/src/api/observable.ts
index 28b83ce40..d4fc1737a 100644
--- a/src/api/observable.ts
+++ b/src/api/observable.ts
@@ -78,7 +78,7 @@ function getEnhancerFromOptions(options: CreateObservableOptions): IEnhancer<any
 function createObservable(v: any, arg2?: any, arg3?: any) {
     // @observable someProp;
     if (typeof arguments[1] === "string") {
-        return deepDecorator.apply(null, arguments)
+        return deepDecorator.apply(null, arguments as any)
     }
 
     // it is an observable already, done
diff --git a/src/api/observe.ts b/src/api/observe.ts
index 4f71cee50..d9e919d4c 100644
--- a/src/api/observe.ts
+++ b/src/api/observe.ts
@@ -9,7 +9,9 @@ import {
     IValueDidChange,
     Lambda,
     ObservableMap,
-    getAdministration
+    getAdministration,
+    ObservableSet,
+    ISetDidChange
 } from "../internal"
 
 export function observe<T>(
@@ -22,6 +24,11 @@ export function observe<T>(
     listener: (change: IArrayChange<T> | IArraySplice<T>) => void,
     fireImmediately?: boolean
 ): Lambda
+export function observe<V>(
+    observableMap: ObservableSet<V>,
+    listener: (change: ISetDidChange<V>) => void,
+    fireImmediately?: boolean
+): Lambda
 export function observe<K, V>(
     observableMap: ObservableMap<K, V>,
     listener: (change: IMapDidChange<K, V>) => void,
diff --git a/src/api/tojs.ts b/src/api/tojs.ts
index 8c13a38de..292c56a51 100644
--- a/src/api/tojs.ts
+++ b/src/api/tojs.ts
@@ -3,7 +3,8 @@ import {
     isObservable,
     isObservableArray,
     isObservableValue,
-    isObservableMap
+    isObservableMap,
+    isObservableSet
 } from "../internal"
 
 export type ToJSOptions = {
@@ -27,7 +28,7 @@ function toJSHelper(source, options: ToJSOptions, __alreadySeen: Map<any, any>)
     if (!options.recurseEverything && !isObservable(source)) return source
 
     if (typeof source !== "object") return source
-    
+
     // Directly return null if source is null
     if (source === null) return null
 
@@ -53,6 +54,22 @@ function toJSHelper(source, options: ToJSOptions, __alreadySeen: Map<any, any>)
         return res
     }
 
+    if (isObservableSet(source) || Object.getPrototypeOf(source) === Set.prototype) {
+        if (options.exportMapsAsObjects === false) {
+            const res = cache(__alreadySeen, source, new Set(), options)
+            source.forEach(value => {
+                res.add(toJSHelper(value, options!, __alreadySeen))
+            })
+            return res
+        } else {
+            const res = cache(__alreadySeen, source, [] as any[], options)
+            source.forEach(value => {
+                res.push(toJSHelper(value, options!, __alreadySeen))
+            })
+            return res
+        }
+    }
+
     if (isObservableMap(source) || Object.getPrototypeOf(source) === Map.prototype) {
         if (options.exportMapsAsObjects === false) {
             const res = cache(__alreadySeen, source, new Map(), options)
diff --git a/src/types/type-utils.ts b/src/types/type-utils.ts
index a843375c4..04bb45a4e 100644
--- a/src/types/type-utils.ts
+++ b/src/types/type-utils.ts
@@ -8,7 +8,8 @@ import {
     isObservableArray,
     isObservableMap,
     isObservableObject,
-    isReaction
+    isReaction,
+    isObservableSet
 } from "../internal"
 
 export function getAtom(thing: any, property?: string): IDepTreeNode {
@@ -21,6 +22,9 @@ export function getAtom(thing: any, property?: string): IDepTreeNode {
                 )
             return (thing as any)[$mobx].atom
         }
+        if (isObservableSet(thing)) {
+            return (thing as any)[$mobx]
+        }
         if (isObservableMap(thing)) {
             const anyThing = thing as any
             if (property === undefined) return anyThing._keysAtom
@@ -66,7 +70,7 @@ export function getAdministration(thing: any, property?: string) {
     if (!thing) fail("Expecting some object")
     if (property !== undefined) return getAdministration(getAtom(thing, property))
     if (isAtom(thing) || isComputedValue(thing) || isReaction(thing)) return thing
-    if (isObservableMap(thing)) return thing
+    if (isObservableMap(thing) || isObservableSet(thing)) return thing
     // Initializers run lazily when transpiling to babel, so make sure they are run...
     initializeInstance(thing)
     if (thing[$mobx]) return thing[$mobx]
@@ -76,7 +80,8 @@ export function getAdministration(thing: any, property?: string) {
 export function getDebugName(thing: any, property?: string): string {
     let named
     if (property !== undefined) named = getAtom(thing, property)
-    else if (isObservableObject(thing) || isObservableMap(thing)) named = getAdministration(thing)
+    else if (isObservableObject(thing) || isObservableMap(thing) || isObservableSet(thing))
+        named = getAdministration(thing)
     else named = getAtom(thing) // valid for arrays as well
     return named.name
 }
diff --git a/src/utils/decorators.ts b/src/utils/decorators.ts
index ab6232762..669bab987 100644
--- a/src/utils/decorators.ts
+++ b/src/utils/decorators.ts
@@ -102,7 +102,7 @@ export function createPropDecorator(
         if (quacksLikeADecorator(arguments)) {
             // @decorator
             decoratorArguments = EMPTY_ARRAY
-            return decorator.apply(null, arguments)
+            return decorator.apply(null, arguments as any)
         } else {
             // @decorator(args)
             decoratorArguments = Array.prototype.slice.call(arguments)
diff --git a/test/base/set.js b/test/base/set.js
index 1e9e7c6ed..e04647ed2 100644
--- a/test/base/set.js
+++ b/test/base/set.js
@@ -237,3 +237,32 @@ test("toStringTag", () => {
     expect(x[Symbol.toStringTag]).toBe("Set")
     expect(Object.prototype.toString.call(x)).toBe("[object Set]")
 })
+
+test("getAtom", () => {
+    var x = set([1])
+    expect(mobx.getAtom(x)).toBeTruthy()
+
+    expect(mobx.isObservableSet(x)).toBeTruthy()
+    expect(mobx.isObservable(x)).toBeTruthy()
+})
+
+test("observe", () => {
+    const vals = []
+    var x = set([1])
+    mobx.observe(x, v => {
+        vals.push(v)
+    })
+    x.add(2)
+    x.add(1)
+    expect(vals).toEqual([{ newValue: 2, object: x, type: "add" }])
+})
+
+test("toJS", () => {
+    const x = mobx.observable({ x: 1 })
+    const y = set([x, 1])
+
+    const z = mobx.toJS(y)
+    expect(z).toEqual([{ x: 1 }, 1])
+    expect(z.x).not.toBe(x)
+    expect(mobx.isObservable(z.x)).toBeFalsy()
+})