diff --git a/date-conversions.cabal b/date-conversions.cabal
--- a/date-conversions.cabal
+++ b/date-conversions.cabal
@@ -1,5 +1,5 @@
 name:                date-conversions
-version:             0.2.0.0
+version:             0.3.0.0
 synopsis:            Date conversions
 description:         Please see README.md
 homepage:            https://github.com/thoughtbot/date-conversions#readme
diff --git a/src/Data/Time/Calendar/DateConversions.hs b/src/Data/Time/Calendar/DateConversions.hs
--- a/src/Data/Time/Calendar/DateConversions.hs
+++ b/src/Data/Time/Calendar/DateConversions.hs
@@ -1,32 +1,33 @@
 module Data.Time.Calendar.DateConversions
-    (
     -- beginning
-      beginningOfWeek
+    ( beginningOfWeek
+    , beginningOfBiweek
     , beginningOfMonth
     , beginningOfQuarter
     , beginningOfYear
-
     -- end
     , endOfWeek
+    , endOfBiweek
     , endOfMonth
     , endOfQuarter
     , endOfYear
-
     -- next
     , nextWeek
+    , nextBiweek
     , nextMonth
     , nextQuarter
     , nextYear
-
     -- previous
     , previousWeek
+    , previousBiweek
     , previousMonth
     , previousQuarter
     , previousYear
     ) where
 
 import qualified Data.Dates as D
-import qualified Data.Time  as T
+import qualified Data.Time as T
+import qualified Data.Time.Calendar.WeekDate as T
 
 beginningOfWeek :: T.Day -> T.Day
 beginningOfWeek d =
@@ -36,6 +37,18 @@
   where
     nextMonday = D.dateTimeToDay . D.nextMonday . D.dayToDateTime
 
+beginningOfBiweek :: T.Day -> T.Day
+beginningOfBiweek d =
+    if odd w'
+        then beginningOfWeek d
+        else T.addDays (-7) $ beginningOfWeek d
+  where
+    (_, w, dow) = T.toWeekDate d
+    w' =
+        if dow == 7
+            then w + 1
+            else w
+
 beginningOfMonth :: T.Day -> T.Day
 beginningOfMonth d = T.fromGregorian year month 1
   where
@@ -55,6 +68,9 @@
 endOfWeek :: T.Day -> T.Day
 endOfWeek = T.addDays 6 . beginningOfWeek
 
+endOfBiweek :: T.Day -> T.Day
+endOfBiweek = T.addDays 13 . beginningOfBiweek
+
 endOfMonth :: T.Day -> T.Day
 endOfMonth = T.addDays (-1) . T.addGregorianMonthsClip 1 . beginningOfMonth
 
@@ -67,6 +83,9 @@
 nextWeek :: T.Day -> T.Day
 nextWeek = T.addDays 7 . beginningOfWeek
 
+nextBiweek :: T.Day -> T.Day
+nextBiweek = T.addDays 14 . beginningOfBiweek
+
 nextMonth :: T.Day -> T.Day
 nextMonth = T.addGregorianMonthsClip 1 . beginningOfMonth
 
@@ -78,6 +97,9 @@
 
 previousWeek :: T.Day -> T.Day
 previousWeek = T.addDays (-7) . beginningOfWeek
+
+previousBiweek :: T.Day -> T.Day
+previousBiweek = T.addDays (-14) . beginningOfBiweek
 
 previousMonth :: T.Day -> T.Day
 previousMonth = T.addGregorianMonthsClip (-1) . beginningOfMonth