Despite its implications for positive youth development, factors and processes that promote civic engagement are critically understudied, particularly among Muslim American adolescents for whom opportunities for civic engagement could be hindered by Islamophobia and hate crimes. Prior work has proposed that parents can strengthen adolescents' group belonging and motivate their civic engagement, but this mediating link has not been empirically tested. Moreover, parents' religious socialization and adolescents' religious identity remain understudied, especially with respect to possible daily fluctuations. We used experience sampling methods to: (a) explore momentary fluctuations and temporal relations between two dimensions of Muslim American adolescents' religious identity (i.e., private regard and centrality) over the course of 14 days (Phase 2), and (b) examine if Muslim American adolescents' momentary religious identity (Phase 2) mediated associations between their stable perceptions of maternal religious socialization (Phase 1) and subsequent civic engagement (Phase 3). Dynamic structural equation modeling revealed positive autoregressive and cross-lagged relations between religious private regard and centrality. Moreover, adolescents' momentary religious identities differentially mediated the associations between maternal religious socialization and civic attitudes and behaviors, suggesting specificity in these developmental processes. Our findings have important implications for programs and policies to support the self-empowerment and positive development of Muslim American adolescents.