ABSTRACT Public views on assigning students mathematics homework have been controversial. Although homework is designed for students to complete during non-school hours (Cooper, 1989), many see homework as excessive pressure on students. Most research placed their focus on the influence of the time spent on homework or the amount of homework on student achievement. Few studies have addressed the impact of types of mathematics homework. The purpose of this study is to examine the role of homework types in influencing opportunity to learn (OTL) on student achievement. This quantitative study used subsets of a large existing dataset collected by University of Chicago School Mathematics Project (UCSMP) in Pre-Transition Mathematics, Transition Mathematics, and Algebra. The findings showed that OTL measured by lesson coverage and by teachers’ reported posttest OTL have significant impact. Each type of homework as a mediator might have significant, positive or negative mediating effects or no mediating effects at all. The findings from having OTL measured by lesson coverage as the independent variable were more consistent with each mathematics course. The differences of the mediating effects of types of homework on the impact of OTL measured by lesson coverage on student mathematics achievement and on the impact of teachers’ reported posttest OTL on students’ mathematics achievement may be explained through the nature of the types of homework as well as through limitations of the study. Recommendations for future research and implications of the study were presented in the discussion part of the study.