The Maricopa County drug court is one of the few post-adjudication drug court programs and one of the first programs to be evaluated with a classic experimental design. The article discusses the design and implementation of the First-Time Drug Offender (FTDO) program within the social and political context of Maricopa County; describes the research design used to study the program implementation and impact; presents the results of RAND’s 12-month evaluation; and discusses the major changes to the drug court program since its inception. The primary feature of the FTDO program that makes it different from other drug courts is the use of a contractual system that specifies consequences and rewards for compliance with the program. In addition, the new drug court has an increased emphasis on cognitive behavioral modeling and relapse prevention, and those offenders who are delinquent in payment of court-ordered fees must attend a financial group. Figures, notes, references