In this study, we explored whether the contribution of working memory (WM) to children's (N = 471) 2nd language (L2) reading and language acquisition was best accounted for by processing efficiency at a phonological level and/or by executive processes independent of phonological processing. Elementary school children (Grades 1, 2, & 3) whose 1st language (L1) was Spanish were administered a battery of cognitive (short-term memory [STM], working memory [WM], rapid naming, and random letter and number generation), vocabulary, and reading measures in both Spanish and English. Hierarchical regression analyses showed that in addition to phonological processing, naming speed, and inattention, both WM and STM contributed significant variance to L2 reading and language acquisition. Regression modeling showed no significant cross-language effects when L1 measures were entered into the analysis. The results showed that both STM and WM contributed unique variance to L2 reading and language acquisition beyond the contribution of L1 phonological processing skills. (Contains 6 tables and 1 footnote.)