Abstinence prior to entering treatment is common among individuals seeking substance abuse treatment. The current study examined the relationship between abstinence at a pretreatment intake assessment and treatment response during outpatient treatment for marijuana dependence. At the intake assessment, 142 marijuana-dependent individuals completed past 30 day calendars of daily drug use. Forty-four (31%) participants were pretreatment abstainers, as defined by reports of one or more consecutive days of marijuana abstinence prior to the day of the intake assessment. Non-abstainers (69%) reported marijuana use the day prior or the day of the assessment. Pretreatment abstainers were more likely to enter treatment (P < 0.05) and showed better treatment response than non-abstainers. Abstainers provided 50% more marijuana-negative urine screens during treatment (P < 0.05), and more than three times as many abstainers reported no marijuana use (P < 0.01). The groups did not differ on treatment completion. Marijuana abstinence at the time of initial clinic contact appears to be a strong predictor of success during treatment. Pretreatment abstinence may prove useful as a pretreatment matching strategy that could improve outcomes and cost-effectiveness. Clinical trials might consider including pretreatment abstinence status as a stratification variable during participant assignment or as a covariate in outcome analyses.