This study addresses the important yet underexplored question of whether the Common Core State Standards in Mathematics, which emphasize critical thinking and problem-solving, as well as the computer-based assessments aligned with the Common Core, have facilitated or hindered learning for students with disabilities. By analyzing administrative data from a large county in California, we track mathematics achievement trends before and after the implementation of the Common Core. Our findings show a significant widening of the achievement disparity in mathematics between students with and without disabilities, suggesting that the Common Core and computerized assessments disproportionately affected students with disabilities.