Modafinil is a medication that may enhance mood and increase energy in cocaine addicts, which may be useful in preventing cocaine relapse. Naltrexone is a medication that is currently used to treat drug and alcohol addiction. A combination of these two medications may be beneficial in reducing drug and alcohol use in individuals undergoing substance abuse treatment. The purpose of this study is to evaluate the effectiveness of modafinil and naltrexone, alone and in combination, at reducing drug and alcohol use in individuals addicted to cocaine and alcohol.