ABSTRACT. Objective: A theory-based protection/risk model was applied to explain variation in college students' heavy episodic drinking. Key aims were (1) to establish that psychosocial and behavioral protective factors and risk factors can account for cross-sectional and developmental variation in heavy episodic drinking, and (2) to examine whether protection moderates the impact of risk on heavy episbdic drinking. Method: Random-and fixed-effects maximum likelihood regression analyses were used to examine data from a three-wave longitudinal study. Data were collected in fall of 2002, spring of 2003, and spring of 2004 from college students (N = 975; 548 men) who were firstsemester freshmen at Wave 1. Results: Psychosocial and behavioral protective and risk factors accounted for substantial variation in collegestudent heavy episodic drinking, and protection moderated the impact of risk. Findings held for both genders and were consistent across the three separate waves of data. Key predictors of heavy episodic drinking were social and individual controls protection (e.g., parental sanctions for transgression and attitudinal intolerance of deviance, respectively); models risk (peer models for substance use); behavioral protection (attendance at religious services); and behavioral risk (cigarette smoking and marijuana use). Changes in controls protection, models risk, and opportunity risk were associated with change in heavy episodic drinking. Conclusions: An explanatory model based on both psychosocial and behavioral protective and risk factors was effective in accounting for variation in college-student heavy episodic drinking. A useful heuristic was demonstrated through the articulation of models, controls, support, opportunity, and vulnerability to characterize the social context, and of controls, vulnerability, and other behaviors to characterize individuals. (J. Stud. Alcohol 67: 86-94, 2006) P ROBLEM USE OF ALCOHOL among college students is a serious public health problem in the United States (Goldman, 2002;Keeling, 1998;Wechsler et al., 2000Wechsler et al., , 2002. Nearly half of college students surveyed reported "getting drunk" as a reason for drinking, and 39%-44% have reported heavy episodic drinking (so-called "binge drinking") (Johnston et al., 2004;Wechsler et al., 2002). Excessive alcohol use adversely affects not only student drinkers, but their peers as well (Abbey, 2002;Hingson et at., 2002Hingson et at., , 2005 Meilman, 1993;Perkins, 2002;Wechsler et al., 1998aWechsler et al., , 2002.This study tests an explanatory model of both proximal and distal psychosocial and behavioral protective factors and risk factors as an account of heavy episodic drinking in a college student sample. It also investigates whether developmental change in these protective and risk factors is related to change in heavy episodic drinking over the first 2 years of college. In recent years, there has been a growing interest in the role of protective factors and risk factors in influencing adolescents' involvement in pr...