Abstract The popular claim that homework time is positively related to achievement and achievement gains was tested in three studies. Time on homework was compared and contrasted with other indicators of homework assignment (i.e., homework frequency) and students' homework behavior (i.e., homework effort). The results of the three studies indicate that homework assignments are positively associated with achievement (class-level effect) and that doing homework is associated with achievement gains (student-level effect), but that the positive effects of homework assignments and completion are not captured by the “time on homework” measure.