This project was begun in response to a Request for Proposals by the National Institute of Child Health & Human Development (NICHD). NICHD sought proposals to evaluate integrated curriculum that targeted skills research deemed important for young children (e.g., early literacy, mathematics, social skills and self-help skills). A strong team of researchers with experience in developing curriculum targeting math knowledge, early literacy and social skills was recruited to participate in a multi-site study. Core components of each curriculum were integrated to provide wide-ranging, age-appropriate curricula for children enrolled in prekindergarten classrooms as well as for younger two to three-year old children. This five-year, multi-site study examined the impact of integrated classroom curricula and teacher professional development on low-income, at-risk children.