Peer-led and adult-led school drug prevention: a meta-analytic comparison.

Several studies have suggested that peer-led drug prevention programs are more effective than adult-led programs, but the evidence is not conclusive. In this article the results are presented of a meta-analysis of studies that compare drug prevention programs led by peers to the same programs led by adults. Twelve studies were identified in a systematic literature search. The quality of these studies was not optimal, and the interventions and target groups differed considerably among studies. Overall, peer-led programs were found to be somewhat more effective than adult-led programs (standardized difference d: 0.24). Large differences between studies were found, with some studies indicating greater effects for peer-led programs and other studies showing greater effects for adult-led programs. It is concluded that the effectiveness of a prevention program is determined by several characteristics of the programs. The leader may constitute one of those characteristics.