diff --git a/core/ManifestBuilder.php b/core/ManifestBuilder.php
index edf5c26c0..5538f2ffe 100644
--- a/core/ManifestBuilder.php
+++ b/core/ManifestBuilder.php
@@ -153,7 +153,7 @@ class ManifestBuilder {
 	 * 
 	 * @param string $baseDir Optional: Absolute path to theme directory for testing e.g. "/Users/sharvey/Sites/test24/themes"
 	 * @param boolean $includeSubThemes If set to TRUE, sub-themes such as "blackcandy_blog" are included too
-	 * @return array indexed array of theme directories
+	 * @return array Listing of theme directories
 	 */
 	public static function get_themes($baseDir = null, $includeSubThemes = false) {
 		// If no base directory specified, the default is the project root
@@ -168,7 +168,7 @@ class ManifestBuilder {
 					if(strpos($file, '_') === false) {
 						$include = true;
 					}
-					if($include) $themes[] = $file;
+					if($include) $themes[$file] = $file;
 				}
 			}
 			closedir($handle);
diff --git a/core/SSViewer.php b/core/SSViewer.php
index 11a044229..5c67392c5 100755
--- a/core/SSViewer.php
+++ b/core/SSViewer.php
@@ -87,6 +87,11 @@ class SSViewer {
 	 */
 	protected static $current_theme = null;
 	
+	/**
+	 * @var string
+	 */
+	protected static $cached_theme = null;
+	
 	/**
 	 * Create a template from a string instead of a .ss file
 	 * 
@@ -106,8 +111,18 @@ class SSViewer {
 	/**
 	 * @return string 
 	 */
-	static function current_theme() {
-		return self::$current_theme;
+	static function current_theme($cached = true) {
+		if($cached && self::$cached_theme) {
+			// First case is to return the cached user theme so we don't requery SiteConfig again
+			return self::$cached_theme;
+		} else {
+			// Need to refresh the cache from the SiteConfig
+			$theme = SiteConfig::current_site_config()->Theme;
+			self::$cached_theme = $theme;
+		}
+		// Fall back to the default SSViewer::set_theme() behaviour
+		if(!$theme) $theme = self::$current_theme;
+		return $theme;
 	}
 	
 	/**
@@ -141,13 +156,13 @@ class SSViewer {
 				else $templateFolder = null;
 
 				// Use the theme template if available
-				if(self::$current_theme && isset($_TEMPLATE_MANIFEST[$template]['themes'][self::$current_theme])) {
+				if(self::current_theme() && isset($_TEMPLATE_MANIFEST[$template]['themes'][self::current_theme()])) {
 					$this->chosenTemplates = array_merge(
-						$_TEMPLATE_MANIFEST[$template]['themes'][self::$current_theme], 
+						$_TEMPLATE_MANIFEST[$template]['themes'][self::current_theme()], 
 						$this->chosenTemplates
 					);
 					
-					if(isset($_GET['debug_request'])) Debug::message("Found template '$template' from main theme '" . self::$current_theme . "': " . var_export($_TEMPLATE_MANIFEST[$template]['themes'][self::$current_theme], true));
+					if(isset($_GET['debug_request'])) Debug::message("Found template '$template' from main theme '" . self::current_theme() . "': " . var_export($_TEMPLATE_MANIFEST[$template]['themes'][self::current_theme()], true));
 				}
 				
 				// Fall back to unthemed base templates
@@ -257,8 +272,8 @@ class SSViewer {
 	 */
 	public static function getTemplateFileByType($identifier, $type) {
 		global $_TEMPLATE_MANIFEST;
-		if(self::$current_theme && isset($_TEMPLATE_MANIFEST[$identifier]['themes'][self::$current_theme][$type])) {
-			return $_TEMPLATE_MANIFEST[$identifier]['themes'][self::$current_theme][$type];
+		if(self::current_theme() && isset($_TEMPLATE_MANIFEST[$identifier]['themes'][self::current_theme()][$type])) {
+			return $_TEMPLATE_MANIFEST[$identifier]['themes'][self::current_theme()][$type];
 		} else if(isset($_TEMPLATE_MANIFEST[$identifier][$type])){
 			return $_TEMPLATE_MANIFEST[$identifier][$type];
 		} else {
diff --git a/core/model/SiteConfig.php b/core/model/SiteConfig.php
index 3b5fd5d53..a63fbe2cd 100644
--- a/core/model/SiteConfig.php
+++ b/core/model/SiteConfig.php
@@ -17,6 +17,7 @@ class SiteConfig extends DataObject {
 	static $db = array(
 		"Title" => "Varchar(255)",
 		"Tagline" => "Varchar(255)",
+		"Theme" => "Varchar(255)",
 		"CanViewType" => "Enum('Anyone, LoggedInUsers, OnlyTheseUsers', 'Anyone')",
 		"CanEditType" => "Enum('LoggedInUsers, OnlyTheseUsers', 'LoggedInUsers')",
 		"CanCreateTopLevelType" => "Enum('LoggedInUsers, OnlyTheseUsers', 'LoggedInUsers')",
@@ -28,6 +29,12 @@ class SiteConfig extends DataObject {
 		"CreateTopLevelGroups" => "Group"
 	);
 	
+	protected static $disabled_themes = array();
+	
+	public static function disable_theme($theme) {
+		self::$disabled_themes[$theme] = $theme;
+	}
+	
 	/**
 	 * Get the fields that are sent to the CMS. In
 	 * your decorators: updateEditFormFields(&$fields)
@@ -39,7 +46,8 @@ class SiteConfig extends DataObject {
 			new TabSet("Root",
 				new Tab('Main',
 					$titleField = new TextField("Title", _t('SiteConfig.SITETITLE', "Site title")),
-					$taglineField = new TextField("Tagline", _t('SiteConfig.SITETAGLINE', "Site Tagline/Slogan"))
+					$taglineField = new TextField("Tagline", _t('SiteConfig.SITETAGLINE', "Site Tagline/Slogan")),
+					new DropdownField("Theme", _t('SiteConfig.THEME', 'Theme'), $this->getAvailableThemes(), '', null, _t('SiteConfig.DEFAULTTHEME', '(Use default theme)'))
 				),
 				new Tab('Access',
 					new HeaderField('WhoCanViewHeader', _t('SiteConfig.VIEWHEADER', "Who can view pages on this site?"), 2),
@@ -89,6 +97,19 @@ class SiteConfig extends DataObject {
 		$this->extend('updateEditFormFields', $fields);
 		return $fields;
 	}
+
+	/**
+	 * Get all available themes that haven't been marked as disabled.
+	 * @param string $baseDir Optional alternative theme base directory for testing
+	 * @return array of theme directory names
+	 */
+	public function getAvailableThemes($baseDir = null) {
+		$themes = ManifestBuilder::get_themes($baseDir);
+		foreach(self::$disabled_themes as $theme) {
+			if(isset($themes[$theme])) unset($themes[$theme]);
+		}
+		return $themes;
+	}
 	
 	/**
 	 * Get the actions that are sent to the CMS. In
diff --git a/tests/SSViewerTest.php b/tests/SSViewerTest.php
index 62215bc6e..00bdc734e 100644
--- a/tests/SSViewerTest.php
+++ b/tests/SSViewerTest.php
@@ -1,6 +1,30 @@
 <?php
 
 class SSViewerTest extends SapphireTest {
+	
+	/**
+	 * Tests for {@link SSViewer::current_theme()} for different behaviour
+	 * of user defined themes via {@link SiteConfig} and default theme
+	 * when no user themes are defined.
+	 */
+	function testCurrentTheme() {
+		$config = SiteConfig::current_site_config();
+		$oldTheme = $config->Theme;
+		$config->Theme = '';
+		$config->write();
+
+		SSViewer::set_theme('mytheme');
+		$this->assertEquals('mytheme', SSViewer::current_theme(), 'Current theme is the default - user has not defined one');
+
+		$config->Theme = 'myusertheme';
+		$config->write();
+		$this->assertEquals('myusertheme', SSViewer::current_theme(), 'Current theme is a user defined one');
+
+		// Set the theme back to the original
+		$config->Theme = $oldTheme;
+		$config->write();
+	}
+	
 	/**
 	 * Test that a template without a <head> tag still renders.
 	 */
diff --git a/tests/model/SiteConfigTest.php b/tests/model/SiteConfigTest.php
index 9008b7c4d..758dea537 100644
--- a/tests/model/SiteConfigTest.php
+++ b/tests/model/SiteConfigTest.php
@@ -53,6 +53,27 @@ class SiteConfigTest extends SapphireTest {
 		$this->assertFalse($pageEn->canEdit($translatorDe));
 		$this->assertTrue($pageEn->canEdit($translatorEn));
 	}
+
+	function testAvailableThemes() {
+		$config = SiteConfig::current_site_config();
+		$ds = DIRECTORY_SEPARATOR;
+		$testThemeBaseDir = TEMP_FOLDER . $ds . 'test-themes';
+		
+		if(file_exists($testThemeBaseDir)) Filesystem::removeFolder($testThemeBaseDir);
+		mkdir($testThemeBaseDir);
+		mkdir($testThemeBaseDir . $ds . 'blackcandy');
+		mkdir($testThemeBaseDir . $ds . 'blackcandy_blog');
+		mkdir($testThemeBaseDir . $ds . 'darkshades');
+		mkdir($testThemeBaseDir . $ds . 'darkshades_blog');
+		
+		$themes = $config->getAvailableThemes($testThemeBaseDir);
+		$this->assertContains('blackcandy', $themes, 'Test themes contain blackcandy theme');
+		$this->assertContains('darkshades', $themes, 'Test themes contain darkshades theme');
+		
+		SiteConfig::disable_theme('darkshades');
+		$themes = $config->getAvailableThemes($testThemeBaseDir);
+		$this->assertFalse(in_array('darkshades', $themes), 'Darkshades was disabled - it is no longer available');
+	}
 	
 }
 ?>
\ No newline at end of file