The purpose of this study is to investigate whether small group instruction in kindergarten widens or closes the achievement gap in mathematics between EL students and non-EL students. The first objective is to examine whether the impacts of small group instruction on math learning differ between EL kindergartners and their non-EL peers. For example, if small group instruction brings more benefit to ELs than it does to non-ELs, then grouping may have the potential of helping EL students to catch up in math learning. If the opposite is true, then grouping may leave EL students further behind academically. However, even if small group instruction is beneficial to the ELs, it may not lead to a substantial reduction in achievement gap if ELs have less access to grouped instruction in comparison with their non-EL peers. Conversely, if grouping practices occur at the detriment of EL students, overuse of this practice could also exacerbate achievement disparities. Therefore, the second objective is to examine whether ELs and non-ELs have equal opportunities for small group instruction in kindergarten. If the use of grouping differs between the two groups, we ask the extent to which the amount of change in math achievement gap between ELs and non-ELs over the kindergarten year is attributable to their differential access to small group instruction. The authors make distinctions among within class homogeneous grouping, mixed ability grouping, and alternate use of both. Additionally, given past research evidence (Hong & Hong, 2009), we allow grouping effects to depend on math instruction time. (Contains 4 tables.)