Group-randomized trials (GRTs)--studies that evaluate the efficacy or effectiveness of interventions occurring at the group level--are increasingly used to assess the effects of school-based prevention programs on behavioral outcomes of children and adolescents. These designs pose many implementation and design challenges for school…

In an attempt to lessen academic failure during the early years of schooling, 23 middle class kindergarten children who scored low on tests of cognitive development were given a special 6-week summer enrichment program. A control group of 23 low scorers received no enrichment program. Parents of the experimental subjects were invited to visit the…

In this study, the authors compared differences in sexual risk attitudes and intentions for three groups of youth (experimental program, n = 90; attention control, n = 80; and nonparticipant control, n = 634) aged 12-14 years. Two student groups participated with their parents in programs focused on strengthening family interaction and prevention…