Data from the National Educational Longitudinal Study (National Educational Longitudinal Study, (1994). NationalEducational Longitudinal Study: second follow-up (Report No.94-374). Washington, DC: U.S. Department of Education] show that on standardised scores in mathematics, reading and science, the highest mean scores are obtained by Asians and whites and lower scores are obtained by Hispanics and blacks. The same differences are present for the number of hours per week devoted to homework. It is suggested that motivational differences expressed in the amount of homework undertaken contribute to the group differences in educational achievement. Statistically significant correlations between the amount of homework and educational achievement support this hypothesis. There are also group differences in intelligence parallel to those in educational achievement, suggesting both intelligence and motivation are involved in racial and ethnic differences in educational achievement.