In 2 studies, an expectancy-value framework was applied to investigate effort expended on mathematics homework. In Study 1 (2,712 students in grades 5, 7, and 9; mean age=13.37 years), lower homework effort was found in higher grades. The effects of intrinsic value on homework effort were higher in the older cohorts, whereas the effects of the expectancy component were lower. In Study 2 (571 students in grades 8 and 9; mean age=14.72), an expanded expectancy-value framework was found to explain both homework and classwork variables. The means for effort and value were lower for homework than for classwork; these differences were partly moderated by students' conscientiousness. The implications of homework behavior and motivation for developmental research are highlighted.