Working memory growth and early Spanish reading interact to shape reading and math gains for Spanish-English emergent bilinguals

• Spanish-English emergent bilinguals show three working memory (WM) trajectories. • Children’s reading and math gains differed across WM trajectory profiles. • Better early Spanish reading benefited children with high initial WM capacity. Using a nationally representative sample of Spanish-English emergent bilinguals (EBs), I explored the heterogenous latent growth profiles of working memory (WM) trajectories and how children with different WM trajectories vary in their reading and math gains across primary years. Latent class growth analysis revealed three distinct growth trajectories of WM capacity, showing patterns of High Baseline, Low Growth; Moderately Low Baseline, High Growth; and Moderately Low Baseline, Moderate Growth. Children in these three profiles differed on reading and math gains, showing groups with higher baseline and/or faster growth rate of WM having greater reading and math gains. Results also showed that as Spanish-English EBs’ early Spanish reading skills increased, children in the High Baseline, Low Growth group gained more in reading and math, compared to those in the Moderately Low Baseline, High Growth group. Our findings highlight that WM and early Spanish reading may be considered jointly in screening process and designing tailored interventions to meet the diverse needs of Spanish-English EB children and facilitate their development in academic skills.