Rates of gambling and substance use behaviors are elevated among emerging adults (ages 18-24), and these behaviors are individually and jointly associated with a host of negative consequences. Evidence suggests there is significant overlap between these behaviors as well as comorbidity of associated mental disorders (i.e., pathological gambling and substance abuse/dependence). Prior research suggests that a brief in-person delivered personalized feedback intervention (PFI) may be an effective method of reducing these behaviors and their associated consequences among emerging adults. Thus, the purpose of this study is to determine the relative efficacy of an in-person delivered PFI versus a Web-based PFI in reducing gambling, alcohol and marijuana use behaviors and related-consequences in a sample of emerging adults, as well as explore potential moderators and mediators of intervention efficacy and the longevity of intervention effects (over a period of 18-months).