This 4-year study will investigate the effectiveness of methylphenidate for initiating and sustaining abstinence in methamphetamine dependent individuals. Approximately 90 participants seeking treatment for methamphetamine dependence will be enrolled in the study for an initial 2 weeks to establish clinic compliance. During this compliance phase, participants will receive incentives for clinic attendance. After meeting clinic attendance requirements, participants will be randomized to placebo (n = 45) or active study medication (n = 45) conditions, and given 18mg/daily of study drug or placebo for one week, followed by 36mg/daily study drug/placebo for a second week. Finally, participants will be stabilized on 54mg/daily study drug/placebo for the remainder of the study. Placebo participants will be given placebo medications prepared to appear identical to the active medication. In addition, after randomization, all participants will receive motivational incentives for methamphetamine-negative urine tests and begin weekly cognitive behavioral therapy (CBT) provided for the duration of the study.