The 2002 Washington State Legislature directed the Washington State Institute for Public Policy to “report on the cost-effectiveness of existing drug courts in Washington and their impacts on reducing recidivism.” Developed during the 1990s, drug courts use frequent courtroom activity and drug treatment resources in an attempt to modify the criminal behavior of certain drug-involved defendants. The questions for this evaluation are whether drug courts—when compared with regular criminal courts—reduce recidivism and produce more benefits than costs. We found that five of the six adult drug courts we evaluated appear to be cost-beneficial additions to Washington’s criminal justice system. The Institute’s report is contained in two documents: a 12-page report and a technical appendix. A separate executive summary is also provided.