>Rushmore only works when one side of the expression EXACTLY matches the index expression. Neither field1 or field2 match your index expression of field1>field2. If you have an index on field1 or on field2 then your expression would be optimizable. To optimize your index you would need something like (field1>field2) = .T.

You and Barbara both came up with the same answer, which I am sure is correct. I was just assuming that the '=.T.' would be implied. I will try tomorrow. Thanks.