The program project objectives are to determine the: 1) effectiveness of school readiness interventions for 2 to 4 yr old children from poverty in center-based settings, 2) role of teacher behavior change in mediating school readiness, and 3) developmental processes (e.g., social, language, cognitive) that influence intervention efficacy on these outcomes. Approaches to supporting young children's learning across a range of skills (i.e., language, literacy, math, social) have overlooked key areas or attended to them in piecemeal ways. The central theme is to test integrated instructional content and processes on social and cognitive learning and mechanisms that explain how this occurs. Five projects and two cores (Administrative, Statistical/ Measurement) are included. Project 1 (2-3 yr old intervention) will test, in a randomized design, the impact of a cognitive curriculum with responsive teaching practices in contrast to its pairing with an explicit social curriculum. Project 2 (pre-K intervention) parallels Project 1 goals with a 4 yr old cohort and also examines the advantage of curriculum linked vs. general progress monitoring. Projects 3-5 will examine the developmental processes that explain intervention effects and how the intervention impacts specific developmental areas. Project 3 (social) will examine chains of mediation between the interventions and outcomes that target the role of social-emotional processes (e.g., emotional understanding, effortful control). Project 4 (language, theory of mind) addresses: a) how language growth promotes academic achievement and growth in theory of mind skills and b) the role that home and school language input play in this process. Project 5 (math) examines whether the developmental trajectories of early math domains predict academic outcomes and examines their precursors. This research program will determine the content, processes, and timing necessary to promote school readiness and the mediating and moderating factors and provide important cross-discipline insights into the interrelation of children's cognitive and social skills.