Informed by two theoretical models of homework effects, we extended a model of homework on mathematics achievement in a large sample of Chinese eighth graders. Our model incorporated six clusters of homework variables -- student background factors, homework characteristics, teacher variables, parent variables, student motivation, and homework behavior. Results indicated that mathematics achievement was related to at least one variable for each of the six clusters at the individual level. At the class level, mathematics achievement was associated positively with homework time, frequency, and interest, but negatively with teacher control. Finally, the combination of prior grades in mathematics and homework completion together influenced mathematics achievement. The study highlights the utility of our extended theoretical model for understanding predictive effects on achievement in a non-Western sample. The different norms and practices around homework in China are discussed, as are implications for future research.