The article summarizes estimates of how effective mandatory minimum sentences are at reducing illicit drug use and its consequences. The study emphasized estimating the marginal cost-effectiveness of mandatory minimum sentences at reducing cocaine consumption relative to available alternative programs. Analysis focused on cocaine because by almost any measure it is the most problematic illicit drug for the United States. Analysis considered these policy options: longer sentences, enforcement with conventional sentencing, and treatment, with the two enforcement interventions evaluated for two distinct populations of dealers (typical dealers and federal-level dealers). Mandatory minimum sentences are not as cost-effective as spending additional resources on either enforcement without mandatory minimums or on drug treatment for heavy drug users. Long sentences should be reserved for certain types of very high-level drug dealers. Figures, references