Here is another way to write it...

=SUMIF(A1:A100,"<=1999-12-31",B1:B100)

where the order of the date parts must be as shown (and I changed your < to
<= as I'm pretty sure you want to include each day in 1999 in your
summation). Of course, you could also write it this way as well...

=SUMIF(A1:A100,"<2000-1-1",B1:B100)

saving yourself from having to type 3 extra characters.<g

Rick


"David" wrote in message
...
Hi Group,

Having a little trouble doing a SumIf, have a list of dates and a column I
am trying to sum if the date is less than a certain date. The dates go
back
to 1/1/1999 and I want to sum value that are less than 12/31/1999, as an
example.

Thanks,
David