Participants will be assessed for compliance with medication treatment, withdrawal severity, recent smoking behavior, and cognitive function during treatment visits on Days 1 and 4. On Day 7, following overnight abstinence from smoking, participants will attend a test session that models relapse to smoking. During this session, subjects will have the option to smoke, or to delay smoking in exchange for monetary compensation (45). To examine if mifepristone's proposed therapeutic effects last beyond the treatment duration (as observed in previous studies), there will be 1-week and 1-month follow-up assessments on smoking behavior, urges to smoke, endocrine biomarkers, and cognitive function.