A review of the significant research on gender differences in test performance is provided, including studies documenting these differences and theories forwarded for the factors related to differential test performance. Research covered addresses undergraduate admissions tests, graduate and professional school admission tests, validity studies, national studies, verbal ability tests, quantitative ability tests, and voluntary testing programs. Specific testing programs discussed include the National Assessment of Educational Progress, National Longitudinal Study of 1972, High School and Beyond study, and Scholastic Aptitude Test. Efforts at explaining performance differences include biological, social, psychological, demographic, and educational factors as well as test characteristics. In so far as there is convergence among studies, it appears that the disparities between the sexes are slowly diminishing. Males have caught up with females in tests of verbal ability and achievement, while females have narrowed the gap between themselves and their male counterparts in the area of mathematics achievement. Concern continues over social implications of the slight differences in performance. A 235-item list of references and six flowcharts are provided. A bibliography of pertinent references, arranged by format and topic, is appended. (TJH)