diff --git a/src/Expectation.php b/src/Expectation.php
index 2afe4088..7da35974 100644
--- a/src/Expectation.php
+++ b/src/Expectation.php
@@ -52,6 +52,101 @@ final class Expectation
         return $this;
     }
 
+    /**
+     * Assert that value is false.
+     */
+    public function toBeFalse()
+    {
+        Assert::assertFalse($this->value);
+
+        return $this;
+    }
+
+    /**
+     * Assert that value is greater than expected one.
+     *
+     * @param int|float $value
+     */
+    public function toBeGreaterThan($value)
+    {
+        Assert::assertGreaterThan($value, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Assert that value is greater than or equal to the expected one.
+     *
+     * @param int|float $value
+     */
+    public function toBeGreaterThanOrEqual($value)
+    {
+        Assert::assertGreaterThanOrEqual($value, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Assert that value is less than or equal to the expected one.
+     *
+     * @param int|float $value
+     */
+    public function toBeLessThan($value)
+    {
+        Assert::assertLessThan($value, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Assert that value is less than the expected one.
+     *
+     * @param int|float $value
+     */
+    public function toBeLessThanOrEqual($value)
+    {
+        Assert::assertLessThanOrEqual($value, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Assert that needles is an element of value.
+     *
+     * @param mixed $needle
+     */
+    public function toContain($needle)
+    {
+        Assert::assertContains($needle, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Assert that needles is a substring of value.
+     *
+     * @param string $needle
+     */
+    public function toContainString($needle)
+    {
+        Assert::assertStringContainsString($needle, $this->value);
+
+        return $this;
+    }
+
+    /**
+     * Assert that needles is a substring of value, ignoring the
+     * difference in casing.
+     *
+     * @param string $needle
+     */
+    public function toContainStringIgnoringCase($needle)
+    {
+        Assert::assertStringContainsStringIgnoringCase($needle, $this->value);
+
+        return $this;
+    }
+
     /**
      * Dynamically calls methods on the class without any arguments.
      *
diff --git a/tests/Expect/toBeFalse.php b/tests/Expect/toBeFalse.php
new file mode 100644
index 00000000..1371c86e
--- /dev/null
+++ b/tests/Expect/toBeFalse.php
@@ -0,0 +1,15 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('strict comparisons', function () {
+    expect(false)->toBeFalse();
+});
+
+test('failures', function () {
+    expect('')->toBeFalse();
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(false)->not->toBe(false);
+})->throws(ExpectationFailedException::class);
diff --git a/tests/Expect/toBeGreatherThan.php b/tests/Expect/toBeGreatherThan.php
new file mode 100644
index 00000000..ed840ed6
--- /dev/null
+++ b/tests/Expect/toBeGreatherThan.php
@@ -0,0 +1,16 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('passes', function () {
+    expect(42)->toBeGreaterThan(41);
+    expect(4)->toBeGreaterThan(3.9);
+});
+
+test('failures', function () {
+    expect(4)->toBeGreaterThan(4);
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(5)->not->toBeGreaterThan(4);
+})->throws(ExpectationFailedException::class);
diff --git a/tests/Expect/toBeGreatherThanOrEqual.php b/tests/Expect/toBeGreatherThanOrEqual.php
new file mode 100644
index 00000000..3b1cd029
--- /dev/null
+++ b/tests/Expect/toBeGreatherThanOrEqual.php
@@ -0,0 +1,16 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('passes', function () {
+    expect(42)->toBeGreaterThanOrEqual(41);
+    expect(4)->toBeGreaterThanOrEqual(4);
+});
+
+test('failures', function () {
+    expect(4)->toBeGreaterThanOrEqual(4.1);
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(5)->not->toBeGreaterThanOrEqual(5);
+})->throws(ExpectationFailedException::class);
diff --git a/tests/Expect/toBeLessThan.php b/tests/Expect/toBeLessThan.php
new file mode 100644
index 00000000..08db8545
--- /dev/null
+++ b/tests/Expect/toBeLessThan.php
@@ -0,0 +1,16 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('passes', function () {
+    expect(41)->toBeLessThan(42);
+    expect(4)->toBeLessThan(5);
+});
+
+test('failures', function () {
+    expect(4)->toBeLessThan(4);
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(5)->not->toBeLessThan(6);
+})->throws(ExpectationFailedException::class);
diff --git a/tests/Expect/toBeLessThanOrEqual.php b/tests/Expect/toBeLessThanOrEqual.php
new file mode 100644
index 00000000..c9f00577
--- /dev/null
+++ b/tests/Expect/toBeLessThanOrEqual.php
@@ -0,0 +1,16 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('passes', function () {
+    expect(41)->toBeLessThanOrEqual(42);
+    expect(4)->toBeLessThanOrEqual(4);
+});
+
+test('failures', function () {
+    expect(4)->toBeLessThanOrEqual(3.9);
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect(5)->not->toBeLessThanOrEqual(5);
+})->throws(ExpectationFailedException::class);
diff --git a/tests/Expect/toContain.php b/tests/Expect/toContain.php
new file mode 100644
index 00000000..ce477fbf
--- /dev/null
+++ b/tests/Expect/toContain.php
@@ -0,0 +1,15 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('passes', function () {
+    expect([1, 2, 42])->toContain(42);
+});
+
+test('failures', function () {
+    expect([1, 2, 42])->toContain(3);
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect([1, 2, 42])->not->toContain(42);
+})->throws(ExpectationFailedException::class);
diff --git a/tests/Expect/toContainString.php b/tests/Expect/toContainString.php
new file mode 100644
index 00000000..03f55b69
--- /dev/null
+++ b/tests/Expect/toContainString.php
@@ -0,0 +1,16 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('is case sensitive', function () {
+    expect('hello world')->toContainString('world');
+    expect('hello world')->not->toContainString('World');
+});
+
+test('failures', function () {
+    expect('hello world')->toContainString('Hello');
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect('hello world')->not->toContainString('hello');
+})->throws(ExpectationFailedException::class);
diff --git a/tests/Expect/toContainStringIgnoringCase.php b/tests/Expect/toContainStringIgnoringCase.php
new file mode 100644
index 00000000..fc5e1081
--- /dev/null
+++ b/tests/Expect/toContainStringIgnoringCase.php
@@ -0,0 +1,17 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+test('ignore difference in casing', function () {
+    expect('hello world')->toContainStringIgnoringCase('world');
+    expect('hello world')->toContainStringIgnoringCase('World');
+});
+
+test('failures', function () {
+    expect('hello world')->toContainStringIgnoringCase('hi');
+})->throws(ExpectationFailedException::class);
+
+test('not failures', function () {
+    expect('hello world')->not->toContainStringIgnoringCase('Hello');
+    expect('hello world')->not->toContainStringIgnoringCase('hello');
+})->throws(ExpectationFailedException::class);