This 14-week study will enroll individuals addicted to both cocaine and alcohol. During a 1-week screening period, potential participants will be required to complete a detoxification program, including stopping all cocaine and alcohol use. Participants will also undergo a physical exam and an electrocardiogram. Blood will be drawn for laboratory tests, and urine tests will be used to screen for the presence of drugs and alcohol. Individuals who complete the screening and meet all study requirements will be permitted to participate in the treatment phase of the study. During the 13-week treatment phase, participants will be randomly assigned to receive modafinil, naltrexone, a combination of modafinil and naltrexone, or placebo. All participants will attend a CBT session once a week. Study visits will take place twice a week. At each visit, a urine test and breathalyzer will be used to screen for the presence of alcohol and drugs. Participants will also complete standardized psychological questionnaires to measure drug and alcohol craving, treatment services received, severity of illness, and withdrawal symptoms. In addition, participants will meet weekly with a nurse practitioner, who will dispense study medications, monitor adverse events, and evaluate the participant's clinical status. A follow-up evaluation will occur 6 months following the end of treatment.