Previous research indicates that the work of women is often devalued rela- tive to that of men. Two experiments tested the hypothesis that such sex bias appears when judges follow ambiguous guidelines or criteria in making evalua- tions, but not when they tollow clear evaluation guidelines. In each experiment, male and female undergraduates evaluated a performance that was attributed to either a man or woman (an intellectual test performance in Experiment I; an artistic craft object in Experiment 11). Subjects followed either clear, explicit evaluation criteria or vague, ambiguous criteria. As predicted, female subjects Lyaluated the “female's” performance less favorably than the “male's” only when. criteria were vague. In contast, male subjects showed little evidence of sex bias, regardless of the criteria they followed. Discussion centers upon: (1) possible cognitive processes underlying the observed effects of clear criteria; and (2) potential practical applications designed to alleviate sex bias in naturalistic settings.