The purpose of this article is to review both main findings and secondary analyses from studies of abstinence incentives conducted in the National Drug Abuse Treatment Clinical Trials Network (CTN). Previous research has supported the efficacy of tangible incentives provided contingent on evidence of recent drug abstinence. CTN conducted the first multisite effectiveness trial of this novel intervention. Study participants were stimulant abusers (N = 803) participating in treatment at 14 clinical sites and randomly assigned to treatment as usual with or without a prize draw incentive program. Study participants could earn up to $400 over 3 months for submission of drug-free urine and breath (BAL) specimens. Three-month retention was significantly improved by incentives offered to psychosocial counseling clients (50% incentive vs. 35% control retained), whereas ongoing stimulant drug use was significantly reduced in methadone maintenance clients (54.4% incentive vs. 38.7% control samples testing stimulant-negative). In both settings, duration of continuous abstinence achieved was improved in the incentive condition. These studies support effectiveness of one abstinence incentive intervention and highlight the different outcomes that can be expected with application in methadone maintenance versus psychosocial counseling treatment settings. Secondary analyses have shown the importance of early treatment positive versus negative urine screens in moderating the outcome of abstinence incentives and have explored both safety and cost-effectiveness of the intervention. Implications for the use of motivational incentive methods in clinical practice are discussed.