This two-and-a-half year design project will examine associations between the quality of early care and education settings and child outcomes, asking whether certain thresholds of quality or dosage need to be met or particular aspects of quality need to be present before links are apparent. The project is intended to provide guidance to ACF, other federal agencies and other stakeholders to guide new research on the quality of early care and education; support quality improvement initiatives and practice; and inform policy decision-making at the state and national levels. The project will focus on center-based settings serving children from birth through age 5, focusing on children from low-income families. The research questions are: (1) What specific features of quality in center-based early care and education for children from birth to age five lead to gains in child outcomes?; (2) Are there thresholds of quality above and below which the strength of the associations between quality and child outcomes differ? For example is there a level of quality above which improvements are associated with accelerated gains in child outcomes?; (3) Is there a minimum threshold of quality necessary to affect child outcomes?; (4) Do greater dosages of quality care lead to greater gains in child outcomes?; (5) How do quality features, thresholds and dosage relate independently to child outcomes? In relation to one another?; (6) How well are existing measures of quality care capturing these thresholds and dosages?