The bioecological perspective emphasizes that proximal processes are the primary mechanisms driving development. Proximal processes can be influenced by a single microsystem or multiple microsystems collectively, which is defined as the mesosystem. Language brokering and ethnic-racial socialization are important proximal processes in U.S. Latinx families, and are likely to be influenced by the ethnic-racial compositions within families’ ecologies. In this dissertation, I examined these important family processes in relation to the ecologies that Latinx adolescents and/or parents are situated within.Paper 1 examined the developmental trajectories of everyday, school, and official business language brokering, and the influences of neighborhood ethnic-racial compositions on language brokering. Findings showed that language brokering trajectories differed across situations. Neighborhood ethnic-racial compositions influenced language brokering trajectories. Overall, this study addressed the gap in foundational understanding of how language brokering unfolds across developmental time and highlighted neighborhood as a key context shaping the development of language brokering. In paper 2, I used a person-centered approach to capture the ethnic-racial exposures within Latina mothers’ mesosystems using activity space methods, and identified four distinct profiles of mothers navigating distinct activity spaces. Mothers' activity space profiles directly impacted adolescents' ethnic-racial identity. Latina mothers’ activity spaces also influenced adolescent ethnic-racial identity through changes in mothers' cultural socialization. This study offered a holistic view of the varied ethnic-racial exposures encountered by different groups of Latina mothers in their daily activities. This study broadens the existing research by examining Latina mothers' mesosystemic exposures, moving beyond the examination of ethnic-racial socialization and identity within singular microsystems. Both studies centered on Latinx families in emerging immigrant gateways, allowing for the examination of ethnic-racial compositions within a single microsystem and mesosystems at levels not observable in established immigrant gateways. Collectively, the two papers contribute to a comprehensive understanding of U.S. Latinx family processes within ecological contexts over time.