The purpose of this meta-analysis was to determine the relation between mathematics and working memory (WM) and to identify possible moderators of this relation including domains of WM, types of mathematics skills, and sample type. A meta-analysis of 110 studies with 829 effect sizes found a significant medium correlation of mathematics and WM, r = .35, 95% confidence interval .32, .37. Moderation analyses indicated that mathematics showed comparable association with verbal WM, numerical WM, and visuospatial WM. Word-problem solving and whole-number calculations showed the strongest relation with WM whereas geometry showed the weakest relation with WM. The relation between WM and mathematics was stronger among individuals with mathematics difficulties that are associated with other disorders or cognitive deficits compared with that among typically developing individuals and individuals with only mathematics difficulties. The implications of these findings with respect to mathematics instruction and WM training are discussed.