Currently, no effective pharmacological treatment exists for cocaine dependence. Long-term use of cocaine disrupts normal glutamate levels. If addicts stop using cocaine, glutamate levels drop, which encourages addicts to continue seeking the drug. NAC is a drug that increases intracellular cysteine levels, which in turn leads to normalization of glutamate levels. Currently, NAC is used for the treatment of cystic fibrosis, heart disease, and acetaminophen overdose. Since NAC has the capability of restoring normal glutamate levels, it holds potential as a treatment for cocaine dependence. The purpose of this study is to determine the safety and effectiveness of NAC in treating cocaine dependent individuals. In addition, this study will evaluate cocaine craving and withdrawal symptoms in individuals taking NAC.