Memantine is a non-competitive NMDA receptor antagonist that works by decreasing normal excitement in the brain. Dopamine plays a role in the rewarding and addictive properties of cocaine, however, past clinical studies have not been successful in using dopamine agonists in treating cocaine dependent individuals. Non-competitive NMDA receptor antagonists have shown to reduce cocaine-induced dopamine release in animal models and lessen conditioned cocaine cues. This study will evaluate memantine in treating cocaine dependent individuals and its ability to prevent relapse to cocaine use. Specifically, the aim of this study is to determine if memantine is superior to placebo in decreasing cocaine craving, psychological symptoms, functional impairment, and discontinuation of treatment for cocaine abuse.