The proposed investigation will use methadone maintained patients who have concurrent cocaine dependence in order to take advantage of the excellent (over 80%) treatment retention in this patient group and to maximize treatment compliance by daily observed medication with both methadone and levetiracetam. In the initial patients we will explore the tolerability of escalating doses of levetiracetam as well as its potential role in reducing cocaine use, as monitored by self-report and verified by three-times weekly urine toxicology testing in methadone treated patients.The specific aim of this study is to evaluate the tolerability and efficacy of levetiracetam 3 grams/day in modifying cocaine-using behavior, reducing cocaine craving and attenuating cocaine's reinforcing effect among methadone-maintained patients