One way is to use the Sumproduct function. See:
http://www.xldynamic.com/source/xld.SUMPRODUCT.html
Or give us more detail as to what you are trying to sum for specific
examples.

Regards
Rowan

Mike wrote:
What would the form of the function be if I wanted to use the SUMIF funtion
but evaluate two criteria instead of one?

I almost want to use the SUMIF and the AND function.