ABSTRACT. Objective:This meta-analysis examined 53 controlled trials of cognitive-behavioral treatment (CBT) for adults diagnosed with alcohol-or illicit-drug-use disorders. The aims were to provide an overall picture of CBT treatment effi cacy and to identify client or treatment factors predictive of CBT effect magnitude. Method: The inverse variance weighted effect size (Hedges' g) was calculated for each study and pooled using fi xed and random effects methods. Potential study-level moderators were assessed in subgroup analyses by primary drug, type of CBT, and type of comparison condition. In addition, seven client and treatment variables were examined in meta-regression analyses. Results: Across studies, CBT produced a small but statistically signifi cant treatment effect (g = 0.154, p < .005). The pooled effect was somewhat lower at 6-9 months (g = 0.115, p < .005) and continued to diminish at 12-month follow-up (g = 0.096, p < .05). The effect of CBT was largest in marijuana studies (g = 0.513, p < .005) and in studies with a no-treatment control as the comparison condition (g = 0.796, p < .005). Metaregression analyses indicated that the percentage of female participants was positively associated and the number of treatment sessions was negatively associated with effect size. Conclusions: The fi ndings demonstrate the utility of CBT across a large and diverse sample of studies and under rigorous conditions for establishing effi cacy. CBT effects were strongest with marijuana users, when CBT was compared with no treatment, and may be larger with women than with men and when delivered in a brief format. (J. Stud. Alcohol Drugs 70: 516-527, 2009) C OGNITIVE-BEHAVIORAL TREATMENT (CBT) models are among the most extensively evaluated interventions for alcohol-or illicit-drug-use disorders. Based primarily on Marlatt and Gordon's (1985; Marlatt and Donovan, 2005) model of relapse prevention, these treatments target cognitive, affective, and situational triggers for substance use and provide skills training specifi c to coping alternatives. CBT treatment for alcohol or illicit drug use often includes the following strategies: (1) identifying intrapersonal and interpersonal triggers for relapse, (2) coping-skills training, (3) drug-refusal skills training, (4) functional analysis of substance use, and (5) increasing nonuse-related activities. These models have been manualized (e.g., Kadden et al., 1992;Monti et al., 1989) and adapted for implementation in a variety of clinical capacities. Further, CBT interventions have been tested in Stage III research to examine their utility in the "real-world" context, possible adaptations, and costeffectiveness (National Institute on Drug Abuse, 1992; cited from Carroll and Onkin, 2005). As argued by Carroll and Rounsaville (2007), the addictions fi eld would benefi t from greater and continued attention devoted to the dissemination of research-based substance-use treatments. Review data to guide such efforts, however, are needed.CBT interventions for substance-use disorde...