The primary goal of this project is to identify the family and classroom practices/experiences of the Head Start (HS) programs which best promote children’s social emotional development over time. Young children living in low-income families are exposed to a wide array of social and systemic risks which increase the propensity for poor learning and social/emotional development. Head Start aims to support economically disadvantaged children and their families and prepare low-income children for school success by attempting to narrow gaps in school readiness. Supporting positive social emotional development is particularly critical as it likely affects both children's school readiness and future outcomes. This population-based project will be conducted by a team of investigators with extensive expertise in family/classroom practices and child development. We aim: A)To identify social emotional development for HS children, in particular those with disabilities and dual language learners (DLLs); B) To determine how home learning environment and experience and classroom quality contribute to social emotional development of HS children; and C) To investigate the influence of teacher and parent mental health on the association between social contexts and HS children’s social emotional development. The goal of this work is to identify potential malleable social environmental factors that can be targeted through programs and policies to benefit children’s social emotional development, with an emphasis on populations of underserved children in low-resource environments. (author abstract)