diff -rupN ../moodle-2.3/moodle/mod/quiz/lang/en/quiz.php mod/quiz/lang/en/quiz.php
--- ../moodle-2.3/moodle/mod/quiz/lang/en/quiz.php	2012-06-25 12:15:22.000000000 -0500
+++ mod/quiz/lang/en/quiz.php	2012-07-11 07:00:41.351907976 -0500
@@ -87,6 +87,7 @@ $string['attemptnumber'] = 'Attempt';
 $string['attemptquiznow'] = 'Attempt quiz now';
 $string['attempts'] = 'Attempts';
 $string['attemptsallowed'] = 'Attempts allowed';
+$string['attemptsbyenrollment']  = 'Consider attempts for this enrollment only';
 $string['attemptsdeleted'] = 'Quiz attempts deleted';
 $string['attemptselection'] = 'Select which attempts to analyze per user:';
 $string['attemptsexist'] = 'You can no longer add or remove questions.';
@@ -152,6 +152,7 @@ $string['comments'] = 'Comments';
 $string['completedon'] = 'Completed on';
 $string['configadaptive'] = 'If you choose Yes for this option then the student will be allowed multiple responses to a question even within the same attempt at the quiz.';
 $string['configattemptsallowed'] = 'Restriction on the number of attempts students are allowed at the quiz.';
+$string['configattemptsbyenrollment']  = 'Grade, and limit by, attempts in this course enrollment only. (False = include all past enrollments courses with this quiz.)';
 $string['configdecimaldigits'] = 'Number of digits that should be shown after the decimal point when displaying grades.';
 $string['configdecimalplaces'] = 'Number of digits that should be shown after the decimal point when displaying grades for the quiz.';
 $string['configdecimalplacesquestion'] = 'Number of digits that should be shown after the decimal point when displaying the grade for individual questions.';
diff -rupN ../moodle-2.3/moodle/mod/quiz/lib.php mod/quiz/lib.php
--- ../moodle-2.3/moodle/mod/quiz/lib.php	2012-06-25 12:15:22.000000000 -0500
+++ mod/quiz/lib.php	2012-07-11 09:36:40.124882200 -0500
@@ -489,42 +486,32 @@ function quiz_cron() {
  *      array if there are none.
  */
     $previewclause = '';
     if (!$includepreviews) {
         $previewclause = ' AND preview = 0';
     }
 
-    $params['quizid'] = $quizid;
-    $params['userid'] = $userid;
-    return $DB->get_records_select('quiz_attempts',
-            'quiz = :quizid AND userid = :userid' . $previewclause . $statuscondition,
-            $params, 'attempt ASC');
+    if ($quiz->attemptsbyenrollment) {
+        $thisenroltime = '(SELECT MAX({user_enrolments}.timecreated)
+                             FROM {user_enrolments}, {enrol}
+                             WHERE {enrol}.id = {user_enrolments}.enrolid AND {user_enrolments}.userid = {quiz_attempts}.userid AND courseid = ?  )';
+
+        $attempts = $DB->get_records_sql(
+                                          "SELECT *
+                                             FROM {quiz_attempts}
+                                             WHERE quiz=? AND userid=? $previewclause $status_condition[$status] AND timemodified > ($thisenroltime) 
+                                             ORDER BY attempt ASC", array($quizid, $userid, $COURSE->id) );
+    } else {
+        return $DB->get_records_select('quiz_attempts',
+                 'quiz = ? AND userid = ?' . $previewclause . $status_condition[$status],
+                array($quizid, $userid), 'attempt ASC');
+    }
 }
 
diff -rupN ../moodle-2.3/moodle/mod/quiz/mod_form.php mod/quiz/mod_form.php
--- ../moodle-2.3/moodle/mod/quiz/mod_form.php	2012-06-25 12:15:22.000000000 -0500
+++ mod/quiz/mod_form.php	2012-07-11 09:38:17.852989197 -0500
@@ -135,7 +106,20 @@ class mod_quiz_mod_form extends moodlefo
         $mform->setDefault('grademethod', $quizconfig->grademethod);
         $mform->disabledIf('grademethod', 'attempts', 'eq', 1);
 
-        // -------------------------------------------------------------------------------
+        // Grade / restrict access by attempts for this enrollment only, ignoring previous enrollments in courses with this quiz.
+        $mform->addElement('selectyesno', 'attemptsbyenrollment', get_string('attemptsbyenrollment', 'quiz'));
+        $mform->setAdvanced('attemptsbyenrollment', $quizconfig->attemptsbyenrollment_adv);
+        $mform->setDefault('attemptsbyenrollment', $quizconfig->attemptsbyenrollment);
+
         $mform->addElement('header', 'layouthdr', get_string('layout', 'quiz'));
 
         // Shuffle questions.
diff -rupN ../moodle-2.3/moodle/mod/quiz/settings.php mod/quiz/settings.php
--- ../moodle-2.3/moodle/mod/quiz/settings.php	2012-06-25 12:15:22.000000000 -0500
+++ mod/quiz/settings.php	2012-07-11 06:47:13.255008667 -0500
@@ -84,16 +69,22 @@ $quizsettings->add(new mod_quiz_admin_se
         get_string('grademethod', 'quiz'), get_string('configgrademethod', 'quiz'),
         array('value' => QUIZ_GRADEHIGHEST, 'fix' => false), null));
 
+// Grade & limit by all attempts, or only this enrollment
+$quizsettings->add(new admin_setting_configcheckbox_with_advanced('quiz/attemptsbyenrollment',
+        get_string('attemptsbyenrollment', 'quiz'),
+        get_string('configattemptsbyenrollment', 'quiz'),
+        array('value' => 1, 'adv' => true)));
+
// Maximum grade
 $quizsettings->add(new admin_setting_configtext('quiz/maximumgrade',
         get_string('maximumgrade'), get_string('configmaximumgrade', 'quiz'), 10, PARAM_INT));