The questions of whether preschool children benefi t more strongly when early care and education (ECE) is at or above a threshold of quality, has specifi c quality features, and/or is of longer duration were examined in secondary data analyses of eight large ECE studies. These issues are pivotal in recent ECE policies designed to improve school readiness skills, especially for children from low-income families. Threshold analyses examined whether quality had stronger associations with gains in child outcomes in settings with high levels of quality than those with lower quality. Features analyses considered whether specific measures of instruction and of teacher-child interaction were more predictive of gains than global quality measures. Dosage analyses tested whether the amount of in ECE settings or in instruction in specific content areas predicted child outcomes. Threshold analyses provided some evidence for thresholds in measures of instructional quality in relation to reading and language skills in meta-analyses based on a prior-selected cut-points and, less clearly, in empirical methods designed to identify cut-points. Analyses examining quality features indicated stronger prediction of gains in child outcomes from interaction-specific and content-specific measures than from global measures. Propensity score analyses indicated that children had higher school readiness skills at the end of preschool and in kindergarten if they had two years of Head Start compared to one year. Finally, dosage analyses indicated that children showed larger gains in content areas when teachers spent more time providing instruction in those areas or when children had fewer absences. No evidence of quality by quantity interactions emerged. Implications of the thresholds findings for ECE policies such as Quality Rating and Improvement Systems are discussed. The dosage findings support the growing trend toward more than one year of access to publicly funded preschool programs for low-income children as well as increased focus on the content of ECE activities and instruction to enhance language, literacy, and math skills.

Margaret Burchinal is a Senior Scientist at the FPG Child Development Institute and Research Professor of Psychology at the University of North Carolina at Chapel Hill (UNC-CH) and co-principal investigator for the project. She is an applied statistician who specializes in longitudinal data analysis and a developmentalist who is interested in how early childhood policy can provide increased opportunities for all children, especially children from low-income families.

Martha Zaslow is Director of the Office for Policy and Communications of the Society for Research in Child Development and a Senior Scholar at Child Trends, and co-principal investigator for the project. Her research focuses on programs and policies to support the development of young children, and especially measuring and improving quality in early childhood programs. She served as co-principal investigator for this project.

Louisa Tarullo is Associate Director of Research at Mathematica Policy Research and serves as Mathematica's lead for early care and education policy. She directed the OPRE design project which funded the work of this monograph. Her research focuses on programs and policies to support optimal development and learning in children from birth through the early school years.

Elizabeth Votruba-Drzal is an Associate Professor of Psychology and a Center Associate of the Learning Research and Development Center at the University of Pittsburgh. Her research aims to strengthen understanding of how key contexts, including early care and education settings, promote learning and socioemotional development during the transition to school and the early elementary school years.

Portia Miller is a Postdoctoral Scholar at the University of Pittsburgh. Her research interests include poverty's effects on child development, the intersection of poverty and place, and the role of early education in promoting school success.