Nine experiments were performed to verify and extend studies on sex differences in problem solving conducted in the 1950s by Sweeney, Carey, Milton, Nakamura, and Berry. A 20-item set of problems similar to that used by Sweeney et al. was administered to over 1,000 college students using a 3-min per problem time limit. Results indicated that (a) the male advantage, averaging 35% across experiments, persists at the same level as in the 1950s; (b) prior experience with the particular word problems used is unrelated to the sex difference; (c) the sex difference extends to other word problems but not to closed-context reasoning problems or measures of general intelligence; (d) the male advantage is related to similar advantages in spatial and mathematical ability; and (e) aptitude variables dominate attitude and mathematics experience variables in accounting for the sex difference.Reviews of cognitive sex differences over the last two decades are in general agreement that males are superior to females in problem solving. It is not readily perceived, however, that this assertion rests largely on a small number of studies conducted in the 1950s by Sweeney, Milton, Carey, and Nakamura, all of whom were students of Donald Taylor during his years at Stanford University and later at Yale University. As an example of the influence of these studies, eight fairly recent reviews (