While a striking 80% of Latinos ages 5-17 years old report being bilingual in Spanish and English in 2022 (UCLA Latino Policy and Politics Institute, 2022), there remains a critical gap in understanding the cultural processes that cultivate or undermine youth’s effort to preserve their culture through Spanish language use. The present study aims to understand whether parental reports of cultural processes (i.e., ethnic-racial identity, ethnic/cultural values, and cultural socialization) predict adolescents' relational and individual Spanish use. The current study used data from a longitudinal study, the California Families Project (CFP), which interviewed 674 Mexican-origin youth (aged 10-16), and their parents annually. Using the Actor-Partner Interdependence Model (APIM), the current study examined the youth’s own and their parent’s ethnic-racial identity, and ethnic/cultural values, as predictors of youth and parent relational and individual Spanish use. As well as how these associations changed across three time points. Additionally, the study examined a cross-sectional association between child and parent cultural socialization on child relational Spanish use at a single time point. Findings reveal intricate patterns both within individuals in a family, and between family members that contribute to our understanding of the cultural mechanisms that drive Spanish use. More specifically, the study advances the literature by identifying the role of parent-adolescent dynamics in relation to cultural processes that sustain Spanish language use. Finally, the tracking of temporal changes in these associations captures the evolving patterns of language maintenance across development.