Naltrexone is a medication currently used to treat opiate dependence. Naltrexone blocks the euphoric effects of opiates. However, naltrexone treatment suffers from high rates of drop-out and relapse. One possible explanation for this is that opiate addicts continue to experience stress in early recovery from opiate dependence. Lofexidine is an experimental medication currently used in the United Kingdom for opiate detoxification and to treat opiate withdrawal symptoms, including sleep difficulty, muscle pain, anxiety, and tension. The purpose of this study is to examine whether lofexidine in combination with naltrexone can improve an individual's ability to cope with stress. The study will examine whether this, in turn, increases the likelihood that an individual remains abstinent from opiates and maintains recovery for a longer time period.