This meta-analysis synthesized research on math performance outcomes for English learners (EL) as a function of language-focused (math vocabulary) interventions. We included group and single-subject design studies with children from kindergarten to 8th grade (3,766 students for group, 30 for single-subject). Group studies yielded a mean Hedges' g of 0.26 in favor of the interventions relative to the control conditions, whereas single-subject studies yielded a mean Percentage of Non-Overlapping Data of 81.01% and "Phi" coefficient of 0.66 relative to baseline. Although group studies yielded small effect sizes (ESs), we found significant moderators for grade level, intervention focus, and length of intervention. Single-subject studies yielded higher ESs than group studies, and were considered generally effective, with a high ES. This finding was attributed to a direct focus on children with math difficulties and one-to-one instruction. The implications for practice and future research are discussed.