The importance of homework activities for student achievement has been extensively discussed. Research has indicated that, in general, students who spend more time on homework tend to show higher levels of academic achievement. For instance, results from the Third International Mathematics Study (TIMSS) indicated that adolescent students in Japan who showed higher mathematics achievement test scores reported that their teachers more frequently gave them homework. The purpose of this study was to examine relationships between instructional practices, such as homework activities and teaching strategies used when introducing new mathematics topics, and the mathematics achievement of adolescent students in Japan. Further, this study was designed to examine data from the TIMSS 1999 assessment. The initial TIMSS assessment was conducted in 1995 and represented the largest and most comprehensive international comparison of educational contexts and achievement yet conducted. In order to examine the effects of contextual factors on student achievement, a model of achievement was developed which incorporated variables such as classroom environment, instructional practices, family expectations and resources, and student self-beliefs. These results identify a number of instructional practices that are significantly related to the mathematics achievement of adolescent students in Japan. Many of the relationships observed in this study are consistent with findings from previous research.