diff --git a/README.md b/README.md
index d3ba7b033042..6a1e7849bac0 100644
--- a/README.md
+++ b/README.md
@@ -46,6 +46,7 @@ This client supports the following Google Cloud Platform services at an [Alpha](
 * [Google Cloud BigQuery Data Transfer](#google-cloud-bigquery-data-transfer-alpha) (Alpha)
 * [Google Cloud IoT](#google-cloud-iot-alpha) (Alpha)
 * [Google Cloud Redis](#google-cloud-redis-alpha) (Alpha)
+* [Google Cloud Security Command Center](#google-cloud-security-command-center-alpha) (Alpha)
 * [Google Cloud Speech](#google-cloud-speech-alpha) (Alpha)
 * [Google Cloud Talent Solution](#google-cloud-talent-solution-alpha) (Alpha)
 * [Google Stackdriver Debugger](#google-stackdriver-debugger-alpha) (Alpha)
@@ -1263,6 +1264,37 @@ foreach ($response->iterateAllElements() as $instance) {
 $ composer require google/cloud-redis
 ```
 
+## Google Cloud Security Command Center (Alpha)
+
+- [API Documentation](http://googleapis.github.io/google-cloud-php/#/docs/latest/securitycenter/securitycenterclient)
+- [Official Documentation](https://cloud.google.com/security-command-center/docs)
+
+#### Preview
+
+```php
+require 'vendor/autoload.php';
+
+use Google\Cloud\SecurityCenter\V1\SecurityCenterClient;
+use Google\Cloud\SecurityCenter\V1\Source;
+
+$security = new SecurityCenterClient();
+$parent = SecurityCenterClient::organizationName('[YOUR ORGANIZATION]');
+$source = new Source([
+    'name' => SecurityCenterClient::sourceName('[YOUR ORGANIZATION]', '[YOUR SOURCE]'),
+    'displayName' => '[YOUR SOURCE]'
+]);
+
+$res = $security->createSource($parent, $source);
+```
+
+#### google/cloud-security-center
+
+[Google Cloud Security Command Center](https://github.com/googleapis/google-cloud-php-security-center) can be installed separately by requiring the [`google/cloud-security-center`](https://packagist.org/packages/google/cloud-security-center) composer package:
+
+```
+$ composer require google/cloud-security-center
+```
+
 ## Google Cloud Speech (Alpha)
 
 - [API Documentation](http://googleapis.github.io/google-cloud-php/#/docs/latest/speech/speechclient)
diff --git a/SecurityCenter/README.md b/SecurityCenter/README.md
index 7be87c81e330..638104b9438a 100644
--- a/SecurityCenter/README.md
+++ b/SecurityCenter/README.md
@@ -34,6 +34,17 @@ on authenticating your client. Once authenticated, you'll be ready to start maki
 ### Sample
 
 ```php
+use Google\Cloud\SecurityCenter\V1\SecurityCenterClient;
+use Google\Cloud\SecurityCenter\V1\Source;
+
+$security = new SecurityCenterClient();
+$parent = SecurityCenterClient::organizationName('[YOUR ORGANIZATION]');
+$source = new Source([
+    'name' => SecurityCenterClient::sourceName('[YOUR ORGANIZATION]', '[YOUR SOURCE]'),
+    'displayName' => '[YOUR SOURCE]'
+]);
+
+$res = $security->createSource($parent, $source);
 ```
 
 ### Version
diff --git a/SecurityCenter/phpunit.xml.dist b/SecurityCenter/phpunit.xml.dist
new file mode 100644
index 000000000000..1c2b8f6b56d2
--- /dev/null
+++ b/SecurityCenter/phpunit.xml.dist
@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit colors="true">
+  <testsuites>
+    <testsuite>
+      <directory>tests/Unit</directory>
+    </testsuite>
+  </testsuites>
+  <filter>
+    <whitelist>
+      <directory suffix=".php">src</directory>
+      <exclude>
+        <directory suffix=".php">src/V[!a-zA-Z]*</directory>
+      </exclude>
+    </whitelist>
+  </filter>
+</phpunit>
diff --git a/SecurityCenter/src/V1/README.md b/SecurityCenter/src/V1/README.md
new file mode 100644
index 000000000000..455cc24ac78d
--- /dev/null
+++ b/SecurityCenter/src/V1/README.md
@@ -0,0 +1,17 @@
+# Google Cloud Security Command Center V1 generated client for PHP
+
+### Sample
+
+```php
+use Google\Cloud\SecurityCenter\V1\SecurityCenterClient;
+use Google\Cloud\SecurityCenter\V1\Source;
+
+$security = new SecurityCenterClient();
+$parent = SecurityCenterClient::organizationName('[YOUR ORGANIZATION]');
+$source = new Source([
+    'name' => SecurityCenterClient::sourceName('[YOUR ORGANIZATION]', '[YOUR SOURCE]'),
+    'displayName' => '[YOUR SOURCE]'
+]);
+
+$res = $security->createSource($parent, $source);
+```
diff --git a/docs/contents/cloud-security-center.json b/docs/contents/cloud-security-center.json
index 984dbdbb6314..844195333145 100644
--- a/docs/contents/cloud-security-center.json
+++ b/docs/contents/cloud-security-center.json
@@ -5,6 +5,19 @@
         {
             "title": "Overview",
             "type": "securitycenter\/readme"
+        },
+        {
+            "title": "v1beta1",
+            "type": "securitycenter\/v1\/readme",
+            "nav": [
+                {
+                    "title": "SecurityCenterClient",
+                    "type": "securitycenter\/v1\/securitycenterclient"
+                }
+            ],
+            "patterns": [
+                "securitycenter\/v1\/\\w{1,}"
+            ]
         }
     ],
     "pattern": "securitycenter\/\\w{1,}"