The present study was conducted to identify predictors of cocaine abstinence during outpatient behavioral treatment for cocaine dependence. Subjects were 52 cocaine-dependent adults. Stepwise logistic regression was used to identify predictors of abstinence during a 12-week treatment program. Demographic, drug use, and other subject characteristics were examined. The single best predictor of cocaine abstinence was whether a significant other participated in treatment. The odds of achieving a criterion level of cocaine abstinence were approximately 20 times greater for subjects who had a significant other participate in treatment. Importantly, significant others participated in a structured form of relationship counseling and behavioral contracting that is well specified and can be readily tested in a prospective, randomized trial. Considering the pressing need for the development of effective treatments for cocaine dependence, such a trial merits consideration.