The evaluation addressed the first 18 months of court operation. The evaluation team interviewed the principal stakeholders in the court; reviewed court documents, files, and procedures; and analyzed participant data collected by the court. Anonymous interviews were conducted with 69 participants in the court to assess their perceptions of court components. Also, the research team spent over 100 hours observing treatment and courtroom proceedings. The evaluation found that the Bronx Treatment Court has successfully implemented a collaborative approach to screen, assess, and monitor people in treatment. In its first 18 months the court enrolled 453 nonviolent drug offenders, most of them pleading to high-level felony charges. The judges, attorneys, and treatment providers involved in the court met regularly to discuss differences and forge compromise agreements on issues such as eligibility and case disposition. Most treatment court defendants were not detained prior to entering the court, thus minimizing costs associated with detention; however, more than 75 percent of participants who entered in the first year were still active, indicating the court's promising retention rates, which may lead to lower recidivism. All treatment court participants were monitored by the court and by treatment programs. The court was able and willing to expand its treatment network four-fold, and it recognized the need for a treatment coordinator to manage the relationship between the court and treatment providers. Program success in implementation was related to early negotiation and collaboration between the court and treatment actors. The teamwork across agencies was a defining characteristics of the court and a crucial achievement. Any cost savings associated with treatment courts are more likely to come from long-term reductions in illegal activity and drug use than in short-term reduction in pretrial detention. 6 tables