=Sumproduct(($A$1:$A$300=True)*($B$1:$B$300=1))

you can't address and entire column using an array formula such as the above
(and wouldn't want to as recalculation would be extremely slow). Use a few
cells as necessary.

There is no ability to have a "nested" countif.

--
Regards,
Tom Ogilvy

"David Taplin" wrote in message
...
Im trying in excel to count 2 columns using the COUNTIF function :

ie COUNTIF (A:A,TRUE)

however how do i countif with 2 columns, ie

COUNTIF (A:A,TRUE) and (B:B='1')

i need to count number of cells where column A = true and column B = 1, ie
a
nested countif

any advice.