This paper reviews the literature on the effects of what children do with their time out of school and the impact of various care arrangements. Much of the research has focused on "latchkey children": children who care for themselves. In this paper, a summary of the research findings on the latchkey group is followed by a review of what is known about children in arrangements that are supervised by adults. Methodological limitations and disparate results preclude the drawing of definitive conclusions from the studies. In spite of this, the continued proliferation of school-age programs makes it imperative that current knowledge of child development and the effects of child care arrangements be used to define and measure the indicators of quality child care for school-age children. Sections concern: (1) research on school-age children; (2) children in self-care; (3) programs for children in self-care; (4) school-age child care programs; (5) definitions of program quality in school-age child care; and (6) lessons for program evaluation, including methodological issues and suggestions for future research. A list of 90 references is included. (RH)