Gender differences in academic achievement have been studied extensively While it is generally agreed that females have a slight advantage on average in verbal abilities and males have a slight advantage on average in mathematics, it is unclear whether these differences have changed over rime. In this paper evidence from seven surveys representative of the United States twelth grade student population and the National Assessment of Educational Progress (NAEP) long term trend data is brought to bear on the magnitude of gender differences in achievement, the level of agreement among different indices of difference, and the stability of these differences over time. These data provide the unique opportunity to not only empirically estimate mean differences, differences in variance, and differences in extreme scores, but also to estimate change over time in all three indices using both the same and different tests over time. Results show that gender differences in mean and variance are small, while differences in extreme scores are often substantial. None of these differences have changed significantly since 1960 with the possible exception of mean differences in mathematics and science. Each of the datasets reflects the racial composition of the national population when properly weighted (i.e. White = 70%, Black = 15%, Hispanic = 10% Other = 5%).
