A study of the relationships among levels of children's language development, quality and positivity of classroom and language environments, adult-child relationships, and child engagement, in a sample of 102 children and 92 child care providers, and a study of the relationship between child care worker educational level and the quality of their classroom language environments, the types of language stimulation used in their classrooms, and the levels of language development of their students, based on data collected from 24 center-based child care providers