This longitudinal study documents the experiences of 3- to 5-year-old children from low-income families in Los Angeles County, CA, in three types of integrative early childhood intervention settings, and assesses the impacts of these interventions on children's early learning in cognitive, language, and social-emotional domains. The study examines specific instructional practices and philosophies, emotional climate, global quality, and caregiver-child relationships in these intervention settings for children at-risk for school difficulties due to low-income and/or English-language-learner status. The three types of intervention settings are publicly-funded center-based programs (such as Head Start and school district early education programs), private non-profit preschools, and family day care networks, all selected because of their focus on serving low-income families, and their focus on improving children's cognitive and social development. Individual children in these three settings, and in a comparison group sampled from waitlists for these services, were observed in their intervention settings and assessed individually to track their development over time in cognitive, language, and social-emotional domains. Analyses will compare development over time for children in intervention and comparison groups, as well as assessing the specific impacts of different instructional practices and intervention features within and across intervention settings. In addition, a cost analysis was conducted, to assess the costs associated with approaches to improving the development of these at-risk children. The longitudinal study includes 300 children and their parents, caregivers, and teachers, followed from age 3 into and through kindergarten. Children in intervention and control groups will be followed over time into whatever early learning setting they attend. The purpose of the study is to identify specific instructional practices and approaches that have the potential to meaningfully enhance children's development prior to school entry, setting the stage for a successful transition into kindergarten, and reducing the likelihood that these at-risk children will be under-prepared for formal schooling.