Baby FACES, Mathematica's descriptive study of Early Head Start, builds on the success of the flagship study of Head Start, the Family and Child Experiences Survey (FACES). Baby FACES, sponsored by the Office of Planning, Research and Evaluation in the Administration for Children and Families, U.S. Department of Health and Human Services, is designed to inform national and local decision-making on early childhood programs and policies. In this summary of results from the third and final report on the study, we offer insight into the experiences and development of 3-year-old children in Early Head Start, and into what predicts family involvement and service quality. The study also reveals key information about how family characteristics, program experiences, and service quality relate to child outcomes. (author abstract)