The proposed project is a two-year longitudinal examination of the adaptation to, and development of, 21/2 year old children in five types of alternative childcare. Types of childcare will include at-home, family day care, nursery school, day care and combination conditions. The issue to be examined is the effect of the complexity of the social environment (i.e., number of adults and peers) on social development. The sample of children recruited at the beginning of the project (Fall, 1987) will be followed for two years. The research plan also includes a unique feature--a built-in replication. A second sample of children will be recruited in the Fall of 1988 and followed for one year. Comparisons of the 1987 and 1988 cohorts will evaluate the measurement procedures and provide evidence for the generality of research findings. Two specific areas of development will be examined. The first will be the development of social interactions with peers focusing especially on play behavior. The second will be so-called "intellectually valuable" experiences present in adult-child social exchanges (Carew, 1980; Clark- Stewart, 1983). Both aspects of development will be examined using naturalistic observations in the childcare settings, and standardized laboratory play sessions. The observational research methodology will employ microcomputer technology to code prerecorded videotapes of children's behavior using a new system of coding and analysis software already developed by the investigators. Data will also be collected from the parents of each child using a standardized battery of questionnaires, and observations of mother-child interactions during laboratory play sessions.