First, you don't need the Lookup, and second, you want Sumif, not Sum.

However, you're trying to sum based on two selections (greater than the 1st of
the month and less than today). To get around this, you have two choices:

1. Add a helper column, say C, with the month (=text(a2,"mmm")). Then you can
use:
=sumif(C:C,text(today(),"mmm"),B:B)

2. Use Sumproduct, as in:

=SUMPRODUCT(A1:A365=DATE(YEAR(TODAY()),MONTH(TODA Y()),1),A1:A365<=TODAY(),B1:B365)

--
Regards,
Fred


"irvine79" wrote in message
...
Any thoughts? I have spreadsheet that has this years dates running down
column A. I then have each day's corresponding production figure running down
column B. I want to assign a function to a cell that will result in the
months cumulative production figure. (I realize I can manually select the
desired Column B cells, but this is not the solution I am looking for)

The formula I have come up with so far is:

=SUM(LOOKUP(TEXT(TODAY(),"mmm"),TEXT(A1:A365,"mmm" ),B1:B365))

For some reason the result is 0. I used the formula auditing tool and came
up with nothing. Any thoughts?

Thanks