With use of web-based homework systems (WBH) increasing in mathematics classrooms, a study was conducted in which 236 secondary mathematics teachers completed a survey assessing the extent to which their beliefs on the effectiveness of WBH varied according to "level of student achievement" and "level of course." Results indicate that teachers judged WBH to be significantly more effective for lower-achieving students and for students enrolled in lower-level courses. These results suggest that increased use of WBH has potential to mitigate achievement gaps in mathematics by supporting the performance of underachieving students. The results also suggest that use of WBH is likely to continue to expand as teachers work to increase student performance, especially among underachievers.