max has the answer, I'll just add that if your sheet names have a space in
them, enclose the sheet names in the formula with single quote marks
(apostrophes) as

=IF('my Data sheet'!A22="single story system",'my Other Sheet'!B5,"")

"RPW" wrote:

I have a workbook with multiple sheets. On one sheet, for cell a22 (which is
a thru g 22, merged), a value is entered, say 'single story system'. I want
another cell (say b18), on another sheet, to pull a value from a third cell
(say b5) on the third sheet, if cell a22 on the first sheet has 'single story
system' as its value.

I hope I have explained this clearly.