The proposed study will look at cocaine dependent individuals and will consist of three consecutive phases: 1) the 2-week outpatient lead-in phase during which behavioral therapy will be administered; 2) the 15-21 day inpatient phase (during which participants will start study medication of levodopa,carbidopa and entacapone (LCE) and will undergo brain imaging and 3) the 24 weeks outpatient treatment trial. The purpose is to see if treatment with LCE may reverse baseline brain deficits and if this change is associated with clinical improvement. Hypothesis is that treatment with LCE, compared to placebo, increases abstinence from cocaine over a 12-week trial in combination with behavioral treatment with voucher incentives.