diff --git a/.travis.yml b/.travis.yml
index 5917fb86..a565d613 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,7 @@ cache:
 notifications:
   email: false
 node_js:
+  - '10'
   - '9'
   - '8'
   - '6'
diff --git a/spec/predicates/isArray.spec.ts b/spec/predicates/isArray.spec.ts
index 62bb0027..a87c2429 100644
--- a/spec/predicates/isArray.spec.ts
+++ b/spec/predicates/isArray.spec.ts
@@ -27,7 +27,7 @@ describe('predicates', () => {
             {},
             false,
             5,
-        ).it('complains if the value is not an array and provides', (value: any) => {
+        ).it('complains if the value is not an array', (value: any) => {
             expect(() => new Strings(value)).to.throw(`Collection should be an array`);
         });
     });
diff --git a/spec/predicates/isBoolean.spec.ts b/spec/predicates/isBoolean.spec.ts
new file mode 100644
index 00000000..1c59d8d8
--- /dev/null
+++ b/spec/predicates/isBoolean.spec.ts
@@ -0,0 +1,34 @@
+import 'mocha';
+import { given } from 'mocha-testdata';
+
+import { ensure, isBoolean, TinyType } from '../../src';
+import { expect } from '../expect';
+
+describe('predicates', () => {
+
+    /** @test {isBoolean} */
+    describe('::isBoolean', () => {
+
+        class MarketingOptIn extends TinyType {
+            constructor(public readonly value: boolean) {
+                super();
+
+                ensure('MarketingOptIn', value, isBoolean());
+            }
+        }
+
+        it('ensures that the argument is a boolean value', () => {
+            expect(new MarketingOptIn(false)).to.not.throw;                  // tslint:disable-line:no-unused-expression
+        });
+
+        given(
+            undefined,
+            null,
+            {},
+            'string',
+            5,
+        ).it('complains if the value is not a boolean', (value: any) => {
+            expect(() => new MarketingOptIn(value)).to.throw(`MarketingOptIn should be a boolean value`);
+        });
+    });
+});
diff --git a/spec/predicates/isNumber.spec.ts b/spec/predicates/isNumber.spec.ts
new file mode 100644
index 00000000..8e9fee0a
--- /dev/null
+++ b/spec/predicates/isNumber.spec.ts
@@ -0,0 +1,44 @@
+import 'mocha';
+import { given } from 'mocha-testdata';
+
+import { ensure, isNumber, TinyType } from '../../src';
+import { expect } from '../expect';
+
+describe('predicates', () => {
+
+    /** @test {isNumber} */
+    describe('::isNumber', () => {
+        class Percentage extends TinyType {
+            constructor(public readonly value: number) {
+                super();
+
+                ensure('Percentage', value, isNumber());
+            }
+        }
+
+        it('ensures that the argument in a number', () => {
+            expect(new Percentage(42)).to.not.throw;                         // tslint:disable-line:no-unused-expression
+        });
+
+        given(
+            1 / 3,
+            0.42,
+            0o3,
+            0xB4D455,
+            NaN,
+            Infinity,
+            -Infinity,
+        ).it('works for any type of number', (value: any) => {
+            expect(() => new Percentage(value)).to.not.throw;                // tslint:disable-line:no-unused-expression
+        });
+
+        given(
+            undefined,
+            null,
+            {},
+            'string',
+        ).it('complains if the value is not a number', (value: any) => {
+            expect(() => new Percentage(value)).to.throw(`Percentage should be a number`);
+        });
+    });
+});
diff --git a/spec/predicates/isString.spec.ts b/spec/predicates/isString.spec.ts
new file mode 100644
index 00000000..3786f979
--- /dev/null
+++ b/spec/predicates/isString.spec.ts
@@ -0,0 +1,33 @@
+import 'mocha';
+import { given } from 'mocha-testdata';
+
+import { ensure, isString, TinyType } from '../../src';
+import { expect } from '../expect';
+
+describe('predicates', () => {
+
+    /** @test {isString} */
+    describe('::isString', () => {
+        class FirstName extends TinyType {
+            constructor(public readonly value: string) {
+                super();
+
+                ensure('FirstName', value, isString());
+            }
+        }
+
+        it('ensures that the argument in a string', () => {
+            expect(new FirstName('Jan')).to.not.throw;                       // tslint:disable-line:no-unused-expression
+        });
+
+        given(
+            undefined,
+            null,
+            {},
+            [],
+            42,
+        ).it('complains if the value is not a string', (value: any) => {
+            expect(() => new FirstName(value)).to.throw(`FirstName should be a string`);
+        });
+    });
+});
diff --git a/src/predicates/index.ts b/src/predicates/index.ts
index ac601a3a..28443b37 100644
--- a/src/predicates/index.ts
+++ b/src/predicates/index.ts
@@ -1,6 +1,7 @@
 export * from './and';
 export * from './hasLengthOf';
 export * from './isArray';
+export * from './isBoolean';
 export * from './isDefined';
 export * from './isEqualTo';
 export * from './isGreaterThan';
@@ -9,6 +10,8 @@ export * from './isInRange';
 export * from './isInteger';
 export * from './isLessThan';
 export * from './isLessThanOrEqualTo';
+export * from './isNumber';
 export * from './isOneOf';
+export * from './isString';
 export * from './or';
 export * from './Predicate';
diff --git a/src/predicates/isBoolean.ts b/src/predicates/isBoolean.ts
new file mode 100644
index 00000000..fd23c837
--- /dev/null
+++ b/src/predicates/isBoolean.ts
@@ -0,0 +1,19 @@
+import { Predicate } from './Predicate';
+
+/**
+ * @desc Ensures that the `value` is a {@link Boolean} value.
+ *
+ * @example
+ * import { ensure, isBoolean, TinyType } from 'tiny-types';
+ *
+ * class MarketingOptIn extends TinyType {
+ *     constructor(public readonly value: boolean) {
+ *         ensure('MarketingOptIn', value, isBoolean());
+ *     }
+ * }
+ *
+ * @returns {Predicate<boolean>}
+ */
+export function isBoolean(): Predicate<boolean> {
+    return Predicate.to(`be a boolean value`, (value: boolean) => typeof value === 'boolean');
+}
diff --git a/src/predicates/isNumber.ts b/src/predicates/isNumber.ts
new file mode 100644
index 00000000..dc77456c
--- /dev/null
+++ b/src/predicates/isNumber.ts
@@ -0,0 +1,19 @@
+import { Predicate } from './Predicate';
+
+/**
+ * @desc Ensures that the `value` is a {@link Number}.
+ *
+ * @example
+ * import { ensure, isNumber, TinyType } from 'tiny-types';
+ *
+ * class Percentage extends TinyType {
+ *     constructor(public readonly value: number) {
+ *         ensure('Percentage', value, isNumber());
+ *     }
+ * }
+ *
+ * @returns {Predicate<number>}
+ */
+export function isNumber(): Predicate<number> {
+    return Predicate.to(`be a number`, (value: number) => typeof value === 'number');
+}
diff --git a/src/predicates/isString.ts b/src/predicates/isString.ts
new file mode 100644
index 00000000..56c92444
--- /dev/null
+++ b/src/predicates/isString.ts
@@ -0,0 +1,19 @@
+import { Predicate } from './Predicate';
+
+/**
+ * @desc Ensures that the `value` is an integer {@link Number}.
+ *
+ * @example
+ * import { ensure, isString, TinyType } from 'tiny-types';
+ *
+ * class FirstName extends TinyType {
+ *     constructor(public readonly value: string) {
+ *         ensure('FirstName', value, isString());
+ *     }
+ * }
+ *
+ * @returns {Predicate<string>}
+ */
+export function isString(): Predicate<string> {
+    return Predicate.to(`be a string`, (value: string) => typeof value === 'string');
+}