PROJECT SUMMARY The overarching goal of the proposed study is to identify the features of Spanish-speaking Latino children's early language learning environments that are associated with positive dual language trajectories and thus provide a scientific basis for interventions and policies aimed at promoting the dual language development and academic well-being of a substantial portion of the U.S. population. Young Latinos are the largest ethnic- minority group in the U.S., representing a quarter of the U.S. population. Latino children from Spanish-speaking homes are typically characterized as underperforming academically in language-related areas such as reading. Such academic difficulties are connected to a myriad of health concerns later in life, including engaging in risky behaviors (e.g., smoking, physical inactivity, obesity), access to low quality healthcare and a low life expectancy. Thus, the academic underperformance and language-related difficulties of Spanish-speaking Latinos represent a national health concern. At the center of policy efforts intended to promote children's language skills and hence, healthy development is exposure to high-quality language experiences or ?language nutrition? (i.e., vocabulary diversity, syntactic complexity). Yet, the pathways underlying ethnic-minority children's successful language development remain understudied. Questions remain, including whether and how Spanish-speaking Latino's early language environments establish a trajectory for dual language growth and ultimately, academic success. Therefore, the proposed study's aims are to 1) describe the trajectories of dual language development in Spanish- speaking Latino toddlers at ages 18, 24, 30 and 36 months, 2) identify the individual child-level factors, including gesture production, that are associated with increases in Spanish-speaking Latino toddler's dual language skills, and 3) identify the features of Spanish-speaking Latino children's language-learning environments, including caregiver language input (i.e., vocabulary, syntax) and emotional supportiveness (i.e., warmth, sensitivity), that are associated with their English and Spanish language skills. Undergraduate and graduate student researchers will collect, transcribe and code video- and audio-recorded observations of caregiver-child language interactions in homes with varying Spanish and English exposure levels. Observations will take place at 6-month intervals, from child age 18 to 36 months, using novel language recording technology. Researcher-developed and standardized tests will be used to assess children's vocabulary and syntactic skills. In addition to identifying protective child- and contextual-level factors related to successful dual language learning in Spanish-speaking Latino toddlers, these study findings will have important implications for interventions and policies aimed at enhancing language and health-related academic outcomes in a substantial portion of the U.S. population.