diff --git a/README.md b/README.md
index f728568..6914e85 100644
--- a/README.md
+++ b/README.md
@@ -41,6 +41,7 @@ You can also group by:
 - hour
 - week
 - month
+- quarter
 - year
 
 and
diff --git a/lib/groupdate.rb b/lib/groupdate.rb
index 9b5c77a..01f146e 100644
--- a/lib/groupdate.rb
+++ b/lib/groupdate.rb
@@ -4,7 +4,7 @@ require "groupdate/version"
 require "groupdate/magic"
 
 module Groupdate
-  FIELDS = [:second, :minute, :hour, :day, :week, :month, :year, :day_of_week, :hour_of_day, :day_of_month, :month_of_year]
+  FIELDS = [:second, :minute, :hour, :day, :week, :month, :quarter, :year, :day_of_week, :hour_of_day, :day_of_month, :month_of_year]
   METHODS = FIELDS.map { |v| :"group_by_#{v}" }
 
   mattr_accessor :week_start, :day_start, :time_zone
diff --git a/lib/groupdate/magic.rb b/lib/groupdate/magic.rb
index 939061d..e6baa04 100644
--- a/lib/groupdate/magic.rb
+++ b/lib/groupdate/magic.rb
@@ -45,6 +45,8 @@ module Groupdate
             ["MONTH(CONVERT_TZ(DATE_SUB(#{column}, INTERVAL #{day_start} HOUR), '+00:00', ?))", time_zone]
           when :week
             ["CONVERT_TZ(DATE_FORMAT(CONVERT_TZ(DATE_SUB(#{column}, INTERVAL ((#{7 - week_start} + WEEKDAY(CONVERT_TZ(#{column}, '+00:00', ?) - INTERVAL #{day_start} HOUR)) % 7) DAY) - INTERVAL #{day_start} HOUR, '+00:00', ?), '%Y-%m-%d 00:00:00') + INTERVAL #{day_start} HOUR, ?, '+00:00')", time_zone, time_zone, time_zone]
+          when :quarter
+            ["DATE_ADD(CONVERT_TZ(DATE_FORMAT(DATE(CONCAT(EXTRACT(YEAR FROM CONVERT_TZ(DATE_SUB(#{column}, INTERVAL #{day_start} HOUR), '+00:00', ?)), '-', LPAD(1 + 3 * (QUARTER(CONVERT_TZ(DATE_SUB(#{column}, INTERVAL #{day_start} HOUR), '+00:00', ?)) - 1), 2, '00'), '-01')), '%Y-%m-%d %H:%i:%S'), ?, '+00:00'), INTERVAL #{day_start} HOUR)", time_zone, time_zone, time_zone]
           else
             format =
               case field
@@ -201,7 +203,11 @@ module Groupdate
           if time_range.first
             series = [round_time(time_range.first)]
 
-            step = 1.send(field)
+            if field == :quarter
+              step = 3.months
+            else
+              step = 1.send(field)
+            end
 
             while (next_step = round_time(series.last + step)) && time_range.cover?(next_step)
               series << next_step
@@ -278,6 +284,8 @@ module Groupdate
           (time - ((7 - week_start + weekday) % 7).days).midnight
         when :month
           time.beginning_of_month
+        when :quarter
+          time.beginning_of_quarter
         when :year
           time.beginning_of_year
         when :hour_of_day
diff --git a/test/test_helper.rb b/test/test_helper.rb
index c9aadf9..f08facc 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -230,6 +230,42 @@ module TestGroupdate
     assert_result_time :month, "2013-03-01 02:00:00 PST", "2013-03-01 10:00:00", true, day_start: 2
   end
 
+  # quarter
+
+  def test_quarter_end_of_quarter
+    assert_result_time :quarter, "2013-04-01 00:00:00 UTC", "2013-06-30 23:59:59"
+  end
+
+  def test_quarter_start_of_quarter
+    assert_result_time :quarter, "2013-04-01 00:00:00 UTC", "2013-04-01 00:00:00"
+  end
+
+  def test_quarter_end_of_quarter_with_time_zone
+    assert_result_time :quarter, "2013-04-01 00:00:00 PDT", "2013-07-01 06:59:59", true
+  end
+
+  def test_quarter_start_of_quarter_with_time_zone
+    assert_result_time :quarter, "2013-04-01 00:00:00 PDT", "2013-04-01 07:00:00", true
+  end
+
+  # quarter starts at 2am
+
+  def test_quarter_end_of_quarter_day_start_2am
+    assert_result_time :quarter, "2013-04-01 02:00:00 UTC", "2013-07-01 01:59:59", false, day_start: 2
+  end
+
+  def test_quarter_start_of_quarter_day_start_2am
+    assert_result_time :quarter, "2013-04-01 02:00:00 UTC", "2013-04-01 02:00:00", false, day_start: 2
+  end
+
+  def test_quarter_end_of_quarter_with_time_zone_day_start_2am
+    assert_result_time :quarter, "2013-01-01 02:00:00 PST", "2013-04-01 08:59:59", true, day_start: 2
+  end
+
+  def test_quarter_start_of_quarter_with_time_zone_day_start_2am
+    assert_result_time :quarter, "2013-01-01 02:00:00 PST", "2013-01-01 10:00:00", true, day_start: 2
+  end
+
   # year
 
   def test_year_end_of_year
@@ -468,6 +504,14 @@ module TestGroupdate
     assert_zeros :month, "2013-04-16 20:00:00 PDT", ["2013-03-01 00:00:00 PST", "2013-04-01 00:00:00 PDT", "2013-05-01 00:00:00 PDT"], "2013-03-01 00:00:00 PST", "2013-05-31 23:59:59 PDT", true
   end
 
+  def test_zeros_quarter
+    assert_zeros :quarter, "2013-04-16 20:00:00 UTC", ["2013-01-01 00:00:00 UTC", "2013-04-01 00:00:00 UTC", "2013-07-01 00:00:00 UTC"], "2013-01-01 00:00:00 UTC", "2013-09-30 23:59:59 UTC"
+  end
+
+  def test_zeros_quarter_time_zone
+    assert_zeros :quarter, "2013-04-16 20:00:00 PDT", ["2013-01-01 00:00:00 PST", "2013-04-01 00:00:00 PDT", "2013-07-01 00:00:00 PDT"], "2013-01-01 00:00:00 PST", "2013-09-30 23:59:59 PDT", true
+  end
+
   def test_zeros_year
     assert_zeros :year, "2013-04-16 20:00:00 UTC", ["2012-01-01 00:00:00 UTC", "2013-01-01 00:00:00 UTC", "2014-01-01 00:00:00 UTC"], "2012-01-01 00:00:00 UTC", "2014-12-31 23:59:59 UTC"
   end
@@ -721,6 +765,11 @@ module TestGroupdate
     assert_format :month, "March 2014", "%B %Y"
   end
 
+  def test_format_quarter
+    create_user "2014-03-05 00:00:00 UTC"
+    assert_format :quarter, "January 1, 2014", "%B %-e, %Y"
+  end
+
   def test_format_year
     create_user "2014-03-01 00:00:00 UTC"
     assert_format :year, "2014", "%Y"
--
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