In an effort to promote evidence-based practice, government officials, researchers, and program developers have developed lists of model programs in the prevention field. This article reviews the evidence used by seven best-practice lists to select five model prevention programs. The authors' examination of this research raises questions about the process used to identify and publicize programs as successful. They found limited evidence showing substantial impact on drug use behavior at posttest, with very few studies showing substantial impact at longer follow-ups. The authors advocate additional long-term follow-up studies and conclude by suggesting changes in the procedures for developing best-practice lists. (Contains 3 tables and 6 endnotes.)