diff --git a/simplenews_scheduler.install b/simplenews_scheduler.install
index b1b3171..63de9e5 100644
--- a/simplenews_scheduler.install
+++ b/simplenews_scheduler.install
@@ -24,6 +24,12 @@ function simplenews_scheduler_schema() {
         'not null' => TRUE,
         'default' => 0,
       ),
+      'next_run' => array(
+        'description' => 'The future timestamp the next scheduled newsletter is due to be sent.',
+        'type' => 'int',
+        'not null' => TRUE,
+        'default' => 0,
+      ),
       'activated' => array(
         'description' => 'Whether the schedule is active.',
         'type' => 'int',
@@ -131,3 +137,40 @@ function simplenews_scheduler_update_7000() {
     db_add_field('simplenews_scheduler', 'title', $field);
   }
 }
+
+/**
+ * Add the next_run field to the scheduler table and populate it.
+ */
+function simplenews_scheduler_update_7001() {
+  // Only act if the field doesn't exist yet: this accounts for the possibility
+  // it's been added in a 62xx update.
+  if (!db_field_exists('simplenews_scheduler', 'next_run')) {
+    // Add the field.
+    $field = array(
+      'description' => 'The future timestamp the next scheduled newsletter is due to be sent.',
+      'type' => 'int',
+      'not null' => TRUE,
+      'default' => 0,
+      'initial' => 0,
+    );
+    db_add_field('simplenews_scheduler', 'next_run', $field);
+
+    // Populate the new field with each schedule's next run time.
+    // Retrieve all records into an associative array keyed by nid.
+    $schedules = db_query("SELECT * FROM {simplenews_scheduler}")->fetchAllAssoc('nid');
+    foreach ($schedules as $nid => $schedule) {
+      // Clone the object to make a fake one to pass to the API.
+      $schedule_copy = clone($schedule);
+      // Remove last_run from the object to force the next_run calculation to
+      // work from the start_date. This ensures that any error in previous
+      // edition dates due to bugs with month length is ignored.
+      // @see http://drupal.org/node/1364784
+      unset($schedule_copy->last_run)
+
+      // Get the next run time relative to the request time.
+      $schedule->next_run = simplenews_scheduler_calculate_next_run_time($schedule_copy, REQUEST_TIME);
+
+      drupal_write_record('simplenews_scheduler', $schedule, 'nid');
+    }
+  }
+}
diff --git a/simplenews_scheduler.module b/simplenews_scheduler.module
index 43dca03..b921e29 100644
--- a/simplenews_scheduler.module
+++ b/simplenews_scheduler.module
@@ -330,13 +330,17 @@ function simplenews_scheduler_cron() {
     // Create a new edition.
     $eid = _simplenews_scheduler_new_edition($newsletter_parent_data->nid, $edition_time);
 
+    // Set the next run time for the edition.
+    $newsletter_parent_data->next_run = simplenews_scheduler_calculate_next_run_time($newsletter_parent_data, $now_time);
+    drupal_write_record('simplenews_scheduler', $newsletter_parent_data, 'nid');
+
     // Send it.
     _simplenews_scheduler_send_new_edition($edition_time, $newsletter_parent_data, $eid);
   }
 }
 
 /**
- * Calculates the next edition time.
+ * Calculates time for the current edition about to be created.
  *
  * Because the scheduler runs according to last_run timestamp and the cron
  * does not run exactly at the scheduled timestamp, this correction fixes
@@ -359,6 +363,46 @@ function simplenews_scheduler_calculate_edition_time($newsletter_parent_data, $n
 }
 
 /**
+ * Calculates time for the next edition to be sent.
+ *
+ * This is set in the {simplenews_scheduler} table when a new edition is run,
+ * for subsequent cron runs to query against.
+ *
+ * The time is strictly in the future; that is, if the $now_time is a valid
+ * edition time, a schedule interval is added to it. This is to allow for cron
+ * runs that need to calculate the next run time at the time of the current
+ * edition being sent.
+ *
+ * @param $newsletter_parent_data
+ *   A row of data from {simplenews_scheduler}, as returned by
+ *   simplenews_scheduler_get_newsletters_due().
+ * @param $now_time
+ *   The time of the operation.
+ *
+ * @return
+ *   The calculcated run time for the next future edition.
+ */
+function simplenews_scheduler_calculate_next_run_time($newsletter_parent_data, $now_time) {
+  // Make an offset string of the format '+1 month'.
+  $offset_string = "+{$newsletter_parent_data->interval_frequency} {$newsletter_parent_data->send_interval}";
+
+  // Set a pointer we'll advance and the increment.
+  if ($newsletter_parent_data->last_run) {
+    $pointer_time = $newsletter_parent_data->last_run;
+  }
+  else {
+    $pointer_time = $newsletter_parent_data->start_date;
+  }
+
+  // Add as many offsets until we get into the future.
+  while ($pointer_time <= $now_time) {
+    // Add increment to the pointer time.
+    $pointer_time = strtotime($offset_string, $pointer_time);
+  }
+  return $pointer_time;
+}
+
+/**
  * Get the newsletters that need to have new editions sent.
  *
  * This is a helper function for hook_cron that has the current date abstracted
@@ -373,52 +417,37 @@ function simplenews_scheduler_calculate_edition_time($newsletter_parent_data, $n
  *  {simplenews_scheduler} table, keyed by newsletter nid.
  */
 function simplenews_scheduler_get_newsletters_due($timestamp) {
-  // Set the default intervals for scheduling.
-  $intervals['hour'] = 3600;
-  $intervals['day'] = 86400;
-  $intervals['week'] = $intervals['day'] * 7;
-  $intervals['month'] = $intervals['day'] * date_days_in_month(date('Y'), date('m'));
-
-  $newsletters = array();
-  foreach ($intervals as $interval => $seconds) {
-    // Check daily items that need to be sent.
-    $sql = "SELECT * FROM {simplenews_scheduler} ";
-    $sql .= "WHERE activated = :active ";
-    $sql .= "AND :now - last_run > :interval ";
-    $sql .= "AND send_interval = :frequency ";
-    $sql .= "AND start_date <= :now ";
-    $sql .= "AND (stop_date > :now OR stop_date = 0)";
-
-    $result = db_query($sql, array(':active' => 1, ':now' => $timestamp, ':interval' => $seconds, ':frequency' => $interval));
-
-    foreach ($result as $newsletter_parent_data) {
-      // The node id of the parent node.
-      $pid = $newsletter_parent_data->nid;
-
-      // Check upon if sending should stop with a given edition number.
-      $stop = $newsletter_parent_data->stop_type;
-      $stop_edition = $newsletter_parent_data->stop_edition;
-
-      $edition_count = db_query('SELECT COUNT(*) FROM {simplenews_scheduler_editions} WHERE pid = :pid', array(':pid' => $pid))->fetchField();
-      // Don't create new edition if the edition number would exceed the given maximum value.
-      if ($stop == 2 && $edition_count >=  $stop_edition) {
-        continue;
-      }
+  // Get all newsletters that need to be sent.
+  $result = db_query("SELECT * FROM {simplenews_scheduler} WHERE activated = 1 AND next_run <= :now AND (stop_date > :now OR stop_date = 0)", array(':now' => $timestamp));
 
-      // does this newsletter have something to evaluate to check running condition?
-      if (strlen($newsletter_parent_data->php_eval)) {
-        $eval_result = eval($newsletter_parent_data->php_eval);
-        if (!$eval_result) {
-          continue;
-        }
-      }
+  foreach ($result as $newsletter_parent_data) {
+    // The node id of the parent node.
+    $pid = $newsletter_parent_data->nid;
 
-      // Add the number of seconds the newsletter's interval represents.
-      $newsletter_parent_data->seconds = $seconds;
+    // Check upon if sending should stop with a given edition number.
+    $stop = $newsletter_parent_data->stop_type;
+    $stop_edition = $newsletter_parent_data->stop_edition;
 
-      $newsletters[$pid] = $newsletter_parent_data;
+    $edition_count = db_query('SELECT COUNT(*) FROM {simplenews_scheduler_editions} WHERE pid = :pid', array(':pid' => $pid))->fetchField();
+    // Don't create new edition if the edition number would exceed the given maximum value.
+    if ($stop == 2 && $edition_count >=  $stop_edition) {
+      continue;
     }
+
+    // does this newsletter have something to evaluate to check running condition?
+    if (strlen($newsletter_parent_data->php_eval)) {
+      $eval_result = eval($newsletter_parent_data->php_eval);
+      if (!$eval_result) {
+        continue;
+      }
+    }
+
+    // Add the number of seconds the newsletter's interval represents.
+    $newsletter_parent_data->seconds = $seconds;
+
+    $newsletters[$pid] = $newsletter_parent_data;
   }
+
   return $newsletters;
 }
 
diff --git a/tests/simplenews_scheduler.test b/tests/simplenews_scheduler.test
index 3aa55a3..1d0d04d 100644
--- a/tests/simplenews_scheduler.test
+++ b/tests/simplenews_scheduler.test
@@ -115,3 +115,140 @@ class SimpleNewsSchedulerNodeCreationTest extends DrupalWebTestCase {
     $this->assertEqual(1, count($mails), t('Newsletter mail has been sent.'));
   }
 }
+
+
+/**
+ * Unit testing for monthly newsletter next run times.
+ */
+class SimpleNewsSchedulerNextRunTimeTest extends DrupalUnitTestCase {
+
+  /**
+   * Provides information about this test.
+   */
+  public static function getInfo() {
+    return array(
+      'name' => 'Next run time: monthly',
+      'description' => 'Testing edition times for newsletters due every month and every 2 months.',
+      'group' => 'Simplenews Scheduler',
+    );
+  }
+
+  /**
+   * Declares the module dependencies.
+   */
+  function setUp() {
+    parent::setUp('simplenews', 'token', 'date', 'simplenews_scheduler');
+  }
+
+  /**
+   * Test a frequency of 1 month.
+   */
+  function testNextRunTimeOneMonth() {
+    // The start date of the edition.
+    $this->edition_day = '05';
+    $start_date = new DateTime("2012-01-{$this->edition_day} 12:00:00");
+
+    // Fake newsletter parent data: sets the interval, start date, and frequency.
+    $newsletter_parent_data = (object) array(
+      'nid' => 1,
+      'last_run' => 0,
+      'activated' => '1',
+      'send_interval' => 'month',
+      'interval_frequency' => '1',
+      'start_date' => $start_date->getTimestamp(),
+      'stop_type' => '0',
+      'stop_date' => '0',
+      'stop_edition' => '0',
+      'php_eval' => '',
+      'title' => '[node:title] for [current-date:long]',
+    );
+
+    // Number of days to run for.
+    $days = 370;
+    // Index of the days we've done so far.
+    $added_days = 0;
+    // Iterate over days.
+    while ($added_days <= $days) {
+      // Create today's date at noon and get the timestamp.
+      $date = clone($start_date);
+      $date->add(new DateInterval("P{$added_days}D"));
+      $timestamp_noon = $date->getTimestamp();
+
+      // Get the next run time from the API function we're testing.
+      $next_run_time = simplenews_scheduler_calculate_next_run_time($newsletter_parent_data, $timestamp_noon);
+      //debug($edition_time);
+
+      $this->assertTrue($timestamp_noon < $next_run_time, t('Next run time of !next-run is in the future relative to current time of !now.', array(
+        '!next-run' => date("Y-n-d H:i:s", $next_run_time),
+        '!now'      => date("Y-n-d H:i:s", $timestamp_noon),
+      )));
+
+      $interval = $newsletter_parent_data->interval_frequency * 31 * 24 * 60 * 60;
+      $this->assertTrue($next_run_time - $timestamp_noon <= $interval, t('Next run timestamp is less than or exactly one month in the future.'));
+
+      // Create a date object from the timestamp. The '@' makes the constructor
+      // consider the string as a timestamp.
+      $next_run_date = new DateTime("@$next_run_time");
+      $d = date_format($next_run_date, 'd');
+      $this->assertEqual($next_run_date->format('d'), $this->edition_day, t('Next run timestamp is on same day of the month as the start date.'));
+
+      $added_days++;
+    } // while days
+  }
+
+  /**
+   * Test a frequency of 2 months.
+   */
+  function testNextRunTimeTwoMonths() {
+    // The start date of the edition.
+    $this->edition_day = '05';
+    $start_date = new DateTime("2012-01-{$this->edition_day} 12:00:00");
+
+    // Fake newsletter parent data: sets the interval, start date, and frequency.
+    $newsletter_parent_data = (object) array(
+      'nid' => 1,
+      'last_run' => 0,
+      'activated' => '1',
+      'send_interval' => 'month',
+      'interval_frequency' => '2',
+      'start_date' => $start_date->getTimestamp(),
+      'stop_type' => '0',
+      'stop_date' => '0',
+      'stop_edition' => '0',
+      'php_eval' => '',
+      'title' => '[node:title] for [current-date:long]',
+    );
+
+    // Number of days to run for.
+    $days = 370;
+    // Index of the days we've done so far.
+    $added_days = 0;
+    // Iterate over days.
+    while ($added_days <= $days) {
+      // Create today's date at noon and get the timestamp.
+      $date = clone($start_date);
+      $date->add(new DateInterval("P{$added_days}D"));
+      $timestamp_noon = $date->getTimestamp();
+
+      // Get the next run time from the API function we're testing.
+      $next_run_time = simplenews_scheduler_calculate_next_run_time($newsletter_parent_data, $timestamp_noon);
+      //debug($edition_time);
+
+      $this->assertTrue($timestamp_noon < $next_run_time, t('Next run time of !next-run is in the future relative to current time of !now.', array(
+        '!next-run' => date("Y-n-d H:i:s", $next_run_time),
+        '!now'      => date("Y-n-d H:i:s", $timestamp_noon),
+      )));
+
+      $interval = $newsletter_parent_data->interval_frequency * 31 * 24 * 60 * 60;
+      $this->assertTrue($next_run_time - $timestamp_noon <= $interval, t('Next run timestamp is less than or exactly two months in the future.'));
+
+      // Create a date object from the timestamp. The '@' makes the constructor
+      // consider the string as a timestamp.
+      $next_run_date = new DateTime("@$next_run_time");
+      $d = date_format($next_run_date, 'd');
+      $this->assertEqual($next_run_date->format('d'), $this->edition_day, t('Next run timestamp is on same day of the month as the start date.'));
+
+      $added_days++;
+    } // while days
+  }
+}