This is a Phase II, randomized, double-blind, placebo-controlled study that will examine the efficacy of extended-release baclofen (Baclofen ER) for the treatment of cocaine dependence. The primary study outcome will be urines positive for benzoylecgonine (BE), a metabolite of cocaine, submitted during outpatient treatment (12-week) and follow-up (12-week). To examine brain mechanisms of relapse/recovery, participants will complete fMRI sessions before, during, and after treatment. Brain responses to specific probes of reward and inhibition will be used as biomarkers predicting drug use during and after the treatment.