The National Drug Abuse Treatment Clinical Trials Network (CTN) began in 2000 with the goal of "improv[ing] the quality of drug abuse treatment throughout the country using science as the vehicle." Since then, 24 discrete clinical trials were launched, 20 are completed, and 15 have published main outcome papers. Of the latter, 4 tested pharmacological treatment, 8 psychosocial/behavioral treatment, 1 a combination of medication and counseling, and 2 targeted HIV/hepatitis C virus risk behavior. We review main study findings for these trials, including treatment retention, substance use or risk behavior outcomes, and secondary outcomes when analyzed. The purpose of this review is to identify the incremental progress toward improving drug treatment made by these trials and to propose next steps for the CTN and for the field arising from these studies. The CTN provides a unique opportunity to systematically design trials that incorporate treatment improvements from previous trials and to direct efforts toward innovations most likely to be incorporated into practice.