Zachary,

For example, to get the values for January of this year, with dates in column A and hours in B:

=SUMPRODUCT((A1:A2000=DATE(2006,1,1))*(A1:A2000<D ATE(2006,2,1))*B1:B2000)

Easier would be a pivot table, with the data grouped based on months.

HTH,
Bernie
MS Excel MVP


"Zachary Baker" <Zachary wrote in message
...
I have been given a data set which contains work hours and dates in the form
of mm/dd/yy. I am trying to sum all the hours worked in each month. A
co-worker suggested I use sumproduct but I'm still not able to achieve the
process. Additionally, the data crosses over years, so I am not quite sure
how to create a fomula that takes the year into account. Any help would be
great. Thanks much.

--
Zachary Baker