Alcohol is a contributing factor in 38.7 percent of U.S. traffic fatalities (NHTSA, 1998). A disproportionate number of these fatalities are caused by drivers previously convicted of driving under the influence (DUI) of intoxicants (Fell, 1990). In addition to the accident risk they pose, DUI offenders are at high risk for future DUI offenses. In California, approximately 35 percent of all DUI convictions are for drivers convicted of DUI within the past 7 years (Peck et al., 1994). Typically, these multiple DUI offenders are found to have alcohol dependence or abuse disorders (Nochajski et al., 1994). These facts highlight the importance of developing criminal justice interventions that address alcoholism and alcohol abuse as a strategy for reducing DUI recidivism. Within criminal justice settings there is a growing optimism that the popular drug court model can be effectively adapted for use with DUI recidivists. This model combines assessment and rapid entry into substance abuse treatment, with court supervision of abstinence and treatment compliance. A consensus statement from many criminal justice organizations calling for a national strategy to promote DUI Courts was issued in 1998 (The Institute, 1999), and the Department of Justice is now offering funds to support the development of such courts. However, no rigorous studies of DUI courts are yet available. Therefore, RAND and the Rio Hondo Municipal Court of Los Angeles propose to conduct an experimental evaluation of a DUI Court modeled on the Rio Hondo Drug Court. Specifically, 330 repeat DUI offenders will be randomly assigned to DUI Court or routine sanctions. In addition to participant interviews conducted before and two years after assignment to condition, criminal, driving, and other official records will be used to evaluate whether DUI Court is associated with: 1) The lowest rates of arrest at follow-up; 2) The fewest incidents of intoxicated driving; 3) Self-reports of less abusive drinking patters; and 4) A more advantageous cost-benefit ratio from the standpoint of the criminal justice system. With jurisdictions across the county considering implementation of DUI Courts, there is a clear and immediate need for information on their effectiveness. The planned evaluation represents a timely and rigorous response to this need.