diff --git a/lib/time_difference.rb b/lib/time_difference.rb
index 73705cf..bc06f9e 100644
--- a/lib/time_difference.rb
+++ b/lib/time_difference.rb
@@ -7,8 +7,8 @@ class TimeDifference
 
   TIME_COMPONENTS = [:years, :months, :weeks, :days, :hours, :minutes, :seconds]
 
-  def self.between(start_time, end_time)
-    new(start_time, end_time)
+  def self.between(start_time, end_time, abs=true)
+    new(start_time, end_time, abs)
   end
 
   def in_years
@@ -78,12 +78,13 @@ def humanize
   end
 
   private
-  
-  def initialize(start_time, end_time)
+
+  def initialize(start_time, end_time, abs=true)
     start_time = time_in_seconds(start_time)
     end_time = time_in_seconds(end_time)
 
-    @time_diff = (end_time - start_time).abs
+    @time_diff = (end_time - start_time)
+    @time_diff = @time_diff.abs if abs
   end
 
   def time_in_seconds(time)