diff --git a/admin/cli/install.php b/admin/cli/install.php
index 3378948d7c3..0631be1c869 100644
--- a/admin/cli/install.php
+++ b/admin/cli/install.php
@@ -70,6 +70,8 @@ Options:
                       problem encountered.
 --agree-license       Indicates agreement with software license,
                       required in non-interactive mode.
+--allow-unstable      Install even if the version is not marked as stable yet,
+                      required in non-interactive mode.
 -h, --help            Print out this help
 
 Example:
@@ -136,9 +138,6 @@ $CFG->early_install_lang   = true;
 $parts = explode('/', str_replace('\\', '/', dirname(dirname(__FILE__))));
 $CFG->admin                = array_pop($parts);
 
-require($CFG->dirroot.'/version.php');
-$CFG->target_release = $release;
-
 //point pear include path to moodles lib/pear so that includes and requires will search there for files before anywhere else
 //the problem is that we need specific version of quickforms and hacked excel files :-(
 ini_set('include_path', $CFG->libdir.'/pear' . PATH_SEPARATOR . ini_get('include_path'));
@@ -154,6 +153,9 @@ require_once($CFG->libdir.'/deprecatedlib.php');
 require_once($CFG->libdir.'/adminlib.php');
 require_once($CFG->libdir.'/componentlib.class.php');
 
+require($CFG->dirroot.'/version.php');
+$CFG->target_release = $release;
+
 //Database types
 $databases = array('mysqli' => moodle_database::get_driver_instance('mysqli', 'native'),
                    'pgsql'  => moodle_database::get_driver_instance('pgsql',  'native'),
@@ -193,6 +195,7 @@ list($options, $unrecognized) = cli_get_params(
         'adminpass'         => '',
         'non-interactive'   => false,
         'agree-license'     => false,
+        'allow-unstable'    => false,
         'help'              => false
     ),
     array(
@@ -402,6 +405,27 @@ $CFG->langotherroot      = $CFG->dataroot.'/lang';
 $CFG->langlocalroot      = $CFG->dataroot.'/lang';
 get_string_manager(true);
 
+// make sure we are installing stable release or require a confirmation
+if (isset($maturity)) {
+    if (($maturity < MATURITY_STABLE) and !$options['allow-unstable']) {
+        $maturitylevel = get_string('maturity'.$maturity, 'admin');
+
+        if ($interactive) {
+            cli_separator();
+            cli_heading(get_string('notice'));
+            echo get_string('maturitycorewarning', 'admin', $maturitylevel) . PHP_EOL;
+            echo get_string('continue') . PHP_LOL;
+            $prompt = get_string('cliyesnoprompt', 'admin');
+            $input = cli_input($prompt, '', array(get_string('clianswerno', 'admin'), get_string('cliansweryes', 'admin')));
+            if ($input == get_string('clianswerno', 'admin')) {
+                exit(1);
+            }
+        } else {
+            cli_error(get_string('maturitycorewarning', 'admin'));
+        }
+    }
+}
+
 // ask for db type - show only drivers available
 if ($interactive) {
     $options['dbtype'] = strtolower($options['dbtype']);
diff --git a/admin/cli/upgrade.php b/admin/cli/upgrade.php
index 142f2d30514..0057426d39e 100644
--- a/admin/cli/upgrade.php
+++ b/admin/cli/upgrade.php
@@ -40,8 +40,16 @@ require_once($CFG->libdir.'/environmentlib.php');
 
 
 // now get cli options
-list($options, $unrecognized) = cli_get_params(array('non-interactive'=>false, 'help'=>false),
-                                               array('h'=>'help'));
+list($options, $unrecognized) = cli_get_params(
+    array(
+        'non-interactive'   => false,
+        'allow-unstable'    => false,
+        'help'              => false
+    ),
+    array(
+        'h' => 'help'
+    )
+);
 
 $interactive = empty($options['non-interactive']);
 
@@ -59,6 +67,8 @@ Site defaults may be changed via local/defaults.php.
 
 Options:
 --non-interactive     No interactive questions or confirmations
+--allow-unstable      Upgrade even if the version is not marked as stable yet,
+                      required in non-interactive mode.
 -h, --help            Print out this help
 
 Example:
@@ -73,7 +83,7 @@ if (empty($CFG->version)) {
     cli_error(get_string('missingconfigversion', 'debug'));
 }
 
-require("$CFG->dirroot/version.php");       // defines $version and $release
+require("$CFG->dirroot/version.php");       // defines $version, $release and $maturity
 $CFG->target_release = $release;            // used during installation and upgrades
 
 if ($version < $CFG->version) {
@@ -93,6 +103,22 @@ if (!check_moodle_environment($version, $environment_results, false, ENV_SELECT_
     exit(1);
 }
 
+// make sure we are upgrading to a stable release or display a warning
+if (isset($maturity)) {
+    if (($maturity < MATURITY_STABLE) and !$options['allow-unstable']) {
+        $maturitylevel = get_string('maturity'.$maturity, 'admin');
+
+        if ($interactive) {
+            cli_separator();
+            cli_heading(get_string('notice'));
+            echo get_string('maturitycorewarning', 'admin', $maturitylevel) . PHP_EOL;
+            cli_separator();
+        } else {
+            cli_error(get_string('maturitycorewarning', 'admin', $maturitylevel));
+        }
+    }
+}
+
 if ($interactive) {
     echo html_to_text(get_string('upgradesure', 'admin', $newversion))."\n";
     $prompt = get_string('cliyesnoprompt', 'admin');
diff --git a/admin/index.php b/admin/index.php
index 14b6f243321..09f79472d30 100644
--- a/admin/index.php
+++ b/admin/index.php
@@ -86,7 +86,7 @@ if (!isset($CFG->version)) {
 
 $version = null;
 $release = null;
-require("$CFG->dirroot/version.php");       // defines $version and $release
+require("$CFG->dirroot/version.php");       // defines $version, $release and $maturity
 $CFG->target_release = $release;            // used during installation and upgrades
 
 if (!$version or !$release) {
@@ -135,9 +135,18 @@ if (!core_tables_exist()) {
         $PAGE->set_cacheable(false);
         echo $OUTPUT->header();
         echo $OUTPUT->heading("Moodle $release");
+
+        if (isset($maturity)) {
+            // main version.php declares moodle code maturity
+            if ($maturity < MATURITY_STABLE) {
+                $maturitylevel = get_string('maturity'.$maturity, 'admin');
+                echo $OUTPUT->box(get_string('maturitycorewarning', 'admin', $maturitylevel), 'generalbox maturitywarning');
+            }
+        }
+
         $releasenoteslink = get_string('releasenoteslink', 'admin', 'http://docs.moodle.org/en/Release_Notes');
         $releasenoteslink = str_replace('target="_blank"', 'onclick="this.target=\'_blank\'"', $releasenoteslink); // extremely ugly validation hack
-        echo $OUTPUT->box($releasenoteslink, 'generalbox boxaligncenter boxwidthwide');
+        echo $OUTPUT->box($releasenoteslink, 'generalbox releasenoteslink');
 
         require_once($CFG->libdir.'/environmentlib.php');
         if (!check_moodle_environment($release, $environment_results, true, ENV_SELECT_RELEASE)) {
@@ -194,6 +203,13 @@ if ($version > $CFG->version) {  // upgrade
         $PAGE->set_heading($stradministration);
         $PAGE->set_cacheable(false);
         echo $OUTPUT->header();
+        if (isset($maturity)) {
+            // main version.php declares moodle code maturity
+            if ($maturity < MATURITY_STABLE) {
+                $maturitylevel = get_string('maturity'.$maturity, 'admin');
+                echo $OUTPUT->box(get_string('maturitycorewarning', 'admin', $maturitylevel), 'generalbox maturitywarning');
+            }
+        }
         $continueurl = new moodle_url('index.php', array('confirmupgrade' => 1));
         $cancelurl = new moodle_url('index.php');
         echo $OUTPUT->confirm(get_string('upgradesure', 'admin', $a->newversion), $continueurl, $cancelurl);
diff --git a/lang/en/admin.php b/lang/en/admin.php
index d11e5ff52d9..178c85c3d24 100644
--- a/lang/en/admin.php
+++ b/lang/en/admin.php
@@ -680,6 +680,13 @@ $string['maintinprogress'] = 'Maintenance is in progress...';
 $string['managelang'] = 'Manage';
 $string['managelicenses'] = 'Manage licences';
 $string['manageqtypes'] = 'Manage question types';
+$string['maturity50'] = 'Alpha';
+$string['maturity100'] = 'Beta';
+$string['maturity150'] = 'Release candidate';
+$string['maturity200'] = 'Stable version';
+$string['maturitycorewarning'] = 'You are going to install or upgrade Moodle to a version marked as "{$a}"
+that is not considered as production-ready yet. Please make sure this is intentional
+and that you are using correct checkout of Moodle source code.';
 $string['maxbytes'] = 'Maximum uploaded file size';
 $string['maxconsecutiveidentchars'] = 'Consecutive identical characters';
 $string['maxeditingtime'] = 'Maximum time to edit posts';
diff --git a/lib/setuplib.php b/lib/setuplib.php
index 12c543d6528..c4b07ee06d1 100644
--- a/lib/setuplib.php
+++ b/lib/setuplib.php
@@ -53,6 +53,14 @@ define('MEMORY_EXTRA', -3);
 /** Extremely large memory limit - not recommended for standard scripts */
 define('MEMORY_HUGE', -4);
 
+/**
+ * Software maturity levels used by the core and plugins
+ */
+define('MATURITY_ALPHA',    50);    // internals can be tested using white box techniques
+define('MATURITY_BETA',     100);   // feature complete, ready for preview and testing
+define('MATURITY_RC',       150);   // tested, will be released unless there are fatal bugs
+define('MATURITY_STABLE',   200);   // ready for production deployment
+
 /**
  * Simple class. It is usually used instead of stdClass because it looks
  * more familiar to Java developers ;-) Do not use for type checking of
diff --git a/theme/standard/style/admin.css b/theme/standard/style/admin.css
index 36b5694eb60..7beb53b6c84 100644
--- a/theme/standard/style/admin.css
+++ b/theme/standard/style/admin.css
@@ -23,6 +23,9 @@
 #page-admin-index .adminerror,
 #page-admin-index .adminwarning {margin:20px;}
 
+#page-admin-index .maturitywarning {margin-left:auto;margin-right:auto;text-align:center;width:60%;background-color:#ffd3d9;}
+#page-admin-index .releasenoteslink {margin-left:auto;margin-right:auto;text-align:center;width:60%;}
+
 #page-admin-enrol .enrolplugintable {width:700px;margin:1em auto;}
 
 #page-admin-report-capability-index #settingsform h2,
@@ -144,4 +147,4 @@ table.flexible .r1 {background-color: #FAFAFA;}
 */
 #page-admin-webservice-service_users .missingcaps {color: #ff6600;font-size: 90%;}
 #page-admin-setting-webservicetokens .missingcaps {color: #ff6600;font-size: 90%;}
-#page-admin-webservice-service_functions .functiondesc {font-size: 90%;}
\ No newline at end of file
+#page-admin-webservice-service_functions .functiondesc {font-size: 90%;}
diff --git a/version.php b/version.php
index 67c36bab5b7..cf98cffa610 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,10 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version = 2011030300.00;  // YYYYMMDD   = date of the last version bump
-                        //         XX = daily increments
 
-$release = '2.0.2+ (Build: 20110303)';  // Human-friendly version name
+$version  = 2011030300.00;              // YYYYMMDD   = date of the last version bump
+                                        //         XX = daily increments
+
+$release  = '2.0.2+ (Build: 20110303)'; // Human-friendly version name
+
+$maturity = MATURITY_STABLE;            // this version's maturity level