This study examined (1) the effects of onset of timing for early nonparental care patterns on later child development, and (2) the effects of length of daily enrollment in care on later cognitive attainment and socioemotional behaviors. Preschool teachers rated 105 middle-class children on the Preschool Behavior Questionnaire (PBQ) and the Preschool Behavior Rating (PBR) instrument. Socioemotional behaviors of preschoolers who had been in full-time care from infancy onward were rated on the PBR as more intellectually competent than children who had not had full-time care. They were also rated on the PBQ as more hostile-aggressive than children who had never had full-time care. A hierarchical aggression analysis revealed that both observed and teacher-rated aggression were predicted more by sex of child, quality of the day-care center (teacher education and employment stability), and family socioeconomic factors, than by length of enrollment in full-time, nonparental care. A reference list of 26 items is included. (BC)