diff --git a/source/index.ts b/source/index.ts
index 57e945c..1667bab 100644
--- a/source/index.ts
+++ b/source/index.ts
@@ -7,6 +7,7 @@ import {ArrayPredicate} from './lib/predicates/array';
 import {DatePredicate} from './lib/predicates/date';
 import {ErrorPredicate} from './lib/predicates/error';
 import {MapPredicate} from './lib/predicates/map';
+import {SetPredicate} from './lib/predicates/set';
 
 /**
  * @hidden
@@ -55,6 +56,10 @@ export interface Ow {
 	 * Test the value to be a Map.
 	 */
 	readonly map: MapPredicate;
+	/**
+	 * Test the value to be a Set.
+	 */
+	readonly set: SetPredicate;
 	/**
 	 * Test the value to be a Function.
 	 */
@@ -161,6 +166,9 @@ Object.defineProperties(main, {
 	map: {
 		get: () => new MapPredicate()
 	},
+	set: {
+		get: () => new SetPredicate()
+	},
 	function: {
 		get: () => new Predicate('function')
 	},
diff --git a/source/lib/predicates/set.ts b/source/lib/predicates/set.ts
new file mode 100644
index 0000000..a3f765f
--- /dev/null
+++ b/source/lib/predicates/set.ts
@@ -0,0 +1,143 @@
+import * as isEqual from 'lodash.isequal';
+import ow from '../..';
+import {Predicate, Context} from './predicate';
+
+export class SetPredicate extends Predicate<Set<any>> {
+	constructor(context?: Context) {
+		super('set', context);
+	}
+
+	/**
+	 * Test a Set to have a specific size.
+	 *
+	 * @param size The size of the Set.
+	 */
+	size(size: number) {
+		return this.addValidator({
+			message: set => `Expected Set to have size \`${size}\`, got \`${set.size}\``,
+			validator: set => set.size === size
+		});
+	}
+
+	/**
+	 * Test an Size to have a minimum size.
+	 *
+	 * @param size The minimum size of the Set.
+	 */
+	minSize(size: number) {
+		return this.addValidator({
+			message: set => `Expected Set to have a minimum size of \`${size}\`, got \`${set.size}\``,
+			validator: set => set.size >= size
+		});
+	}
+
+	/**
+	 * Test an Set to have a maximum size.
+	 *
+	 * @param size The maximum size of the Set.
+	 */
+	maxSize(size: number) {
+		return this.addValidator({
+			message: set => `Expected Set to have a maximum size of \`${size}\`, got \`${set.size}\``,
+			validator: set => set.size <= size
+		});
+	}
+
+	/**
+	 * Test a Set to include all the provided items. The items are tested by identity, not structure.
+	 *
+	 * @param items The items that should be a item in the Set.
+	 */
+	has(...items: any[]) {
+		const missingItems: any[] = [];
+
+		return this.addValidator({
+			message: () => `Expected Set to have items \`${JSON.stringify(missingItems)}\``,
+			validator: set => {
+				for (const item of items) {
+					if (set.has(item)) {
+						continue;
+					}
+
+					missingItems.push(item);
+
+					if (missingItems.length === 5) {
+						return false;
+					}
+				}
+
+				return missingItems.length === 0;
+			}
+		});
+	}
+
+	/**
+	 * Test a Set to include any of the provided items. The items are tested by identity, not structure.
+	 *
+	 * @param items The items that could be a item in the Set.
+	 */
+	hasAny(...items: any[]) {
+		return this.addValidator({
+			message: () => `Expected Set to have any item of \`${JSON.stringify(items)}\``,
+			validator: set => items.some(item => set.has(item))
+		});
+	}
+
+	/**
+	 * Test all the items in the Set to match the provided predicate.
+	 *
+	 * @param predicate The predicate that should be applied against every item in the Set.
+	 */
+	ofType<T>(predicate: Predicate<T>) {
+		let error: string;
+
+		return this.addValidator({
+			message: () => error,
+			validator: set => {
+				try {
+					for (const item of set.keys()) {
+						ow(item, predicate);
+					}
+
+					return true;
+				} catch (err) {
+					error = err.message;
+
+					return false;
+				}
+			}
+		});
+	}
+
+	/**
+	 * Test a Set to be empty.
+	 */
+	get empty() {
+		return this.addValidator({
+			message: set => `Expected Set to be empty, got \`${JSON.stringify(Array.from(set))}\``,
+			validator: set => set.size === 0
+		});
+	}
+
+	/**
+	 * Test a Set to be not empty.
+	 */
+	get nonEmpty() {
+		return this.addValidator({
+			message: () => 'Expected Set to not be empty',
+			validator: set => set.size > 0
+		});
+	}
+
+	/**
+	 * Test a Set to be deeply equal to the provided Set.
+	 *
+	 * @param expected Expected Set to match.
+	 */
+	deepEqual(expected: Set<any>) {
+		return this.addValidator({
+			message: set => `Expected Set to be deeply equal to \`${JSON.stringify(Array.from(expected))}\`, got \`${JSON.stringify(Array.from(set))}\``,
+			validator: set => isEqual(set, expected)
+		});
+	}
+}
diff --git a/source/test/set.ts b/source/test/set.ts
new file mode 100644
index 0000000..818b824
--- /dev/null
+++ b/source/test/set.ts
@@ -0,0 +1,67 @@
+import test from 'ava';
+import m from '..';
+
+test('set', t => {
+	t.notThrows(() => m(new Set(), m.set));
+	t.notThrows(() => m(new Set(['🦄']), m.set));
+	t.throws(() => m(12 as any, m.set), 'Expected argument to be of type `set` but received type `number`');
+});
+
+test('set.size', t => {
+	t.notThrows(() => m(new Set(), m.set.size(0)));
+	t.notThrows(() => m(new Set(['🦄']), m.set.size(1)));
+	t.throws(() => m(new Set(['🦄']), m.set.size(0)), 'Expected Set to have size `0`, got `1`');
+});
+
+test('set.minSize', t => {
+	t.notThrows(() => m(new Set(['🦄']), m.set.minSize(1)));
+	t.notThrows(() => m(new Set(['🦄', '🌈']), m.set.minSize(1)));
+	t.throws(() => m(new Set(['🦄']), m.set.minSize(2)), 'Expected Set to have a minimum size of `2`, got `1`');
+});
+
+test('set.maxSize', t => {
+	t.notThrows(() => m(new Set(['🦄']), m.set.maxSize(1)));
+	t.notThrows(() => m(new Set(['🦄', '🌈']), m.set.maxSize(4)));
+	t.throws(() => m(new Set(['🦄', '🌈']), m.set.maxSize(1)), 'Expected Set to have a maximum size of `1`, got `2`');
+});
+
+test('set.hasKeys', t => {
+	t.notThrows(() => m(new Set(['unicorn']), m.set.has('unicorn')));
+	t.notThrows(() => m(new Set(['unicorn', 'rainbow']), m.set.has('unicorn', 'rainbow')));
+	t.notThrows(() => m(new Set([1, 2]), m.set.has(1, 2)));
+	t.throws(() => m(new Set(['unicorn', 'rainbow']), m.set.has('foo')), 'Expected Set to have items `["foo"]`');
+	t.throws(() => m(new Set(['unicorn', 'foo']), m.set.has('foo', 'bar')), 'Expected Set to have items `["bar"]`');
+	t.throws(() => m(new Set([2, 4]), m.set.has(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)), 'Expected Set to have items `[1,3,5,6,7]`');
+});
+
+test('set.hasAny', t => {
+	t.notThrows(() => m(new Set(['unicorn']), m.set.hasAny('unicorn', 'rainbow')));
+	t.notThrows(() => m(new Set(['unicorn', 'rainbow']), m.set.hasAny('unicorn')));
+	t.notThrows(() => m(new Set([1, 2]), m.set.hasAny(1, 2, 3, 4)));
+	t.throws(() => m(new Set(['unicorn', 'rainbow']), m.set.hasAny('foo')), 'Expected Set to have any item of `["foo"]`');
+});
+
+test('set.ofType', t => {
+	t.notThrows(() => m(new Set(['unicorn']), m.set.ofType(m.string)));
+	t.notThrows(() => m(new Set(['unicorn', 'rainbow']), m.set.ofType(m.string.minLength(3))));
+	t.notThrows(() => m(new Set([1]), m.set.ofType(m.number)));
+	t.throws(() => m(new Set(['unicorn']), m.set.ofType(m.number)), 'Expected argument to be of type `number` but received type `string`');
+});
+
+test('set.empty', t => {
+	t.notThrows(() => m(new Set(), m.set.empty));
+	t.notThrows(() => m(new Set([]), m.set.empty));
+	t.throws(() => m(new Set(['unicorn']), m.set.empty), 'Expected Set to be empty, got `["unicorn"]`');
+});
+
+test('set.notEmpty', t => {
+	t.notThrows(() => m(new Set(['unicorn']), m.set.nonEmpty));
+	t.throws(() => m(new Set(), m.set.nonEmpty), 'Expected Set to not be empty');
+});
+
+test('set.deepEqual', t => {
+	t.notThrows(() => m(new Set(['unicorn']), m.set.deepEqual(new Set(['unicorn']))));
+	t.notThrows(() => m(new Set([{foo: 'bar'}]), m.set.deepEqual(new Set([{foo: 'bar'}]))));
+	t.throws(() => m(new Set(['unicorn']), m.set.deepEqual(new Set(['rainbow']))), 'Expected Set to be deeply equal to `["rainbow"]`, got `["unicorn"]`');
+	t.throws(() => m(new Set([{foo: 'bar'}]), m.set.deepEqual(new Set([{foo: 'baz'}]))), 'Expected Set to be deeply equal to `[{"foo":"baz"}]`, got `[{"foo":"bar"}]`');
+});