If you move the periods to the last column:

12/31/2007 1/27/2008 Period 1
1/28/2008 2/24/2008 Period 2
2/25/2008 3/23/2008 Period 3
3/24/2008 4/20/2008 Period 4
4/21/2008 5/18/2008 Period 5
5/19/2008 6/15/2008 Period 6
6/16/2008 7/13/2008 Period 7
7/14/2008 8/10/2008 Period 8
8/11/2008 9/7/2008 Period 9
9/8/2008 10/5/2008 Period 10
10/6/2008 11/2/2008 Period 11
11/3/2008 11/30/2008 Period 12
12/1/2008 12/28/2008 Period 13


Then VLOOKUP() can be used:

=VLOOKUP(DATEVALUE("9/1/2008"),A1:C13,3)

--
Gary''s Student - gsnu200816


"MrRJ" wrote:

Given a particular date, is there a way that I can distinguish what period it
falls between? I plan on a using an if function combined with another
formula.

What period is 9/1/2008? The answer should be Period 9.
Period 1 12/31/07 01/27/08
Period 2 01/28/08 02/24/08
Period 3 02/25/08 03/23/08
Period 4 03/24/08 04/20/08
Period 5 04/21/08 05/18/08
Period 6 05/19/08 06/15/08
Period 7 06/16/08 07/13/08
Period 8 07/14/08 08/10/08
Period 9 08/11/08 09/07/08
Period 10 09/08/08 10/05/08
Period 11 10/06/08 11/02/08
Period 12 11/03/08 11/30/08
Period 13 12/01/08 12/28/08