2. Subjects must meet DSM-IV criteria for current cocaine dependence. Subjects may meet criteria for abuse, but not dependence on any other substance with the exceptions of nicotine and alcohol. Because of the high comorbidity of cocaine with alcohol and nicotine dependence, excluding nicotine and alcohol dependence would seriously compromise the feasibility of recruitment. Nicotine use immediately prior to the cue exposure/extinction session will be controlled. Although individuals who meet criteria for alcohol dependence will be accepted for study participation, anyone who has a measurable blood alcohol level on the day of the sessions will be excluded as acute alcohol intake can increase serum levels of DCS and lower the seizure threshold.