A 2-week screening period will be followed by an 8-week treatment phase. Participants will be randomly assigned to receive either 200 mg of modafinil, 400 mg of modafinil, or placebo on a daily basis for the 8 weeks of treatment. During this time, participants will be asked to report the number of days that they use and do not use cocaine. This will be confirmed three times a week with urine tests. Mood, level of daytime sleepiness, and symptoms of cocaine withdrawal and cocaine "high" will be evaluated. Compliance with study medication will be assessed with urine and blood tests. Medication side effects will be monitored through physical examinations, routine lab tests, ECGs, and self-reports. Follow-up evaluations will occur 4 and 8 weeks following the end of treatment.