Hi: So let's take a look at one possible (theoretical) example of "fake" data from 2 of the files...If the data looked like something like this for RR1 and RR2: [pre] RR1 Date PRED1 x1 x2 x3 01/01/2010 111 1 2 3 01/02/2010 222 4 5 6 RR2 Date PRED2 y1 y2 x3 01/01/2010 333 4 5 6 01/02/2010 444 7 8 9 01/03/2010 555 9 8 7 [/pre] What would you expect the results to look like: Concatenated Results [pre] Date PRED1 PRED2 01/01/2010 111 . 01/01/2010 . 333 01/02/2010 222 . 01/02/2010 . 444 01/03/2010 . 555 [/pre] Merged or Joined Results [pre] Date PRED1 PRED2 01/01/2010 111 333 01/02/2010 222 444 01/03/2010 . 555 [/pre] The way the data looks and the desired result will determine the method you use to bring the files together, as described here: http://support.sas.com/documentation/cdl/en/lrcon/61722/HTML/default/a001081414.htm cynthia ... View more