 Patients treated for methamphetamine dependence have high rates of relapse, and no pharmacotherapy has yet been demonstrated to be efficacious. Modafinil d, l-2-diphenylmethylsulfinylacetamide is a novel wake- and vigilance-promoting agent that is chemically and pharmacologically dissimilar to CNS stimulants. It is well tolerated and has low abuse liability compared to CNS stimulants. Modafinil is FDA approved for a variety of sleep disorders, may relieve methamphetamine withdrawal symptoms, improves cognitive function, has been shown to reduce cocaine use in dependent users, and is safe when coadministered with intravenous methamphetamine. We will conduct a randomized dose ranging clinical trial of modafinil to establish its safety and efficacy as a pharmacotherapy for methamphetamine dependence. 