This review examines the evidence from recent experimental design evaluations on the impact of after-school programming on youth context (i.e., student location, supervision, and safety); participation in activities; and behavioral, social and emotional, and academic outcomes. This review focuses on program models that are of particular interest to policymakers--programs that include academic support services--for two main reasons. First, 21st CCLC grantees are expected to incorporate academic support services into their programming, and it is likely that a large percentage of after-school programs are now funded with 21st CCLC grants. Second, as part of the No Child Left Behind legislation, the federal government legislated Supplemental Educational Services (SES), including after-school programs, to assist students who attend Title I schools not meeting performance goals. (author abstract)