Purpose: The goals of this study were to evaluate the impact of short-term phonological awareness (PA) instruction presented in children's first language (L1; Spanish) on gains in their L1 and second language (L2; English) and to determine whether relationships exist between vocabulary size, verbal working memory, and PA in Spanish-speaking English language learners (ELLs). Method: Participants included 25 kindergartners who received PA instruction and 10 controls. A 2-way within-subjects repeated measures multivariate analysis of variance (MANOVA) was conducted to evaluate gains. Relationships between PA gains, Spanish and English vocabulary, and memory, as measured using nonword repetition and experimental working memory tasks, were analyzed using correlation and regression analyses. Results: Results indicated significant and equivalent gains in both languages of children in the experimental group and no gains in the control group. Spanish vocabulary size was significantly related to PA gains in both languages and was more strongly related to English gains than was English vocabulary size. The memory tasks predicted gains in each language in distinct ways. Conclusion: Results support the conclusion that PA instruction and strong vocabulary skills in an individual's L1 benefit PA development in both the L1 and L2. Results also indicate that dynamic relationships exist between vocabulary size, storage and processing components of working memory, and PA development in both languages of ELLs. (Contains 5 tables and 1 figure.)