The growth of Latinx populations in the United States has resulted in an increasing number of community-based service-learning (CBSL) opportunities. In particular, the steady growth in Spanish-English dual-language schools and the accompanying staff shortages position elementary classrooms as meaningful settings in which to develop relationships between postsecondary L2 Spanish learners and Spanish-speaking children and adults. This qualitative study investigated a CBSL program in which L2 Spanish learners at an urban university served as weekly teaching assistants at a local dual-language elementary school. Data were collected from 55 reflective blog entries, two focus group sessions, and interviews with four teaching assistants. The L2 Spanish learners reported that the experience supported their language acquisition by (1) providing oral language practice outside of class, (2) facilitating linguistic self-confidence, (3) fostering metacognitive reflection, and (4) transforming motivation and attitudes. Implications are provided regarding ways that the dual-language classroom setting holds promise for engaging L2 Spanish learners at various levels in CBSL.