Methamphetamine use is very common in the US and is associated with serious medical and psychiatric problems. There has also been a significant increase in the number of patients entering treatment for methamphetamine dependence, however, no pharmacologic treatment has been identified as effective in treating methamphetamine addiction. Given that withdrawal from methamphetamine is thought to contribute to relapse to methamphetamine use during early treatment, it is important to examine potential pharmacologic agents for alleviating withdrawal. Thus, this study is designed to study methamphetamine withdrawal in humans. To this end, 30 methamphetamine dependent participants (ages 18-65 years) will be entered into a 4-week residential study. Urine samples will be obtained at baseline to ensure recent methamphetamine use. Intake assessments will include cognitive testing, standardized assessment of depression and anxiety, profile of mood states, methamphetamine selective severity assessment, methamphetamine withdrawal assessment, sleep quality and quantity, a pre-attentional measure and attentional measure. Upon admission to the residential facility, all study participants will be started on (20-30mg) long acting amphetamine/d-amphetamine and stabilized over the first 5 days. After stabilization participants will be randomized based on sex, amphetamine withdrawal questionnaire score, and methamphetamine selective severity assessment score to either continued treatment with amphetamine/d-amphetamine or placebo for 2 weeks. All subjects will then be placed on placebo for the last 7 days. The investigators hypothesis is that stopping amphetamine administration in methamphetamine dependent individuals will negatively impact mood, sleep and cognitive function in a time-limited fashion that may differ depending upon the measure and that attentional, but not pre-attentional, measures will be adversely affected in those receiving placebo compared to those maintained on amphetamine.