Try it this way:

=SUMIF(Sheet1!A:A,"M",Sheet1!B:B)

Or you could put the M into a cell (A1 on Sheet2), then it becomes:

=SUMIF(Sheet1!A:A,A1,Sheet1!B:B)

Hope this helps.

Pete

On Apr 28, 1:02*pm, Matt wrote:
Here is my array:
* * * * Col A * Col B
Row 1 * M * * * 1
Row 2 * M * * * 2
Row 3 * M * * * 3
Row 4 * N * * * 4
Row 5 * N * * * 5

Not sure if the title of my question is correct, but I think I need to use
the VLookup function...I need to achieve the following for a dataset:
Assuming that Column A has a set of some text or codes (in my example just
two--"M" and "N"), and Column B has a set of corresponding numbers, I need to
have a formula (in another worksheet), that totals all values from one code. *
for example, to total all rows where the row code is "M", the answer to the
formula would be "6" (1+2+3), and all rows where the code "N" exists, that
answer would yield the number/value of "9" (4+5).

Hope this is clear, and thanks for any help!