Social Contagion in Drug Use and Sex among College Students

Greg J. Duncan, Northwestern University
Johanne Boisjoly, Université du Québec à Rimouski
Dan Levy, Mathematica Policy Research, Inc.
Michael Kremer, Harvard University
Jacquelynne Eccles, University of Michigan

Past research suggests that congregating delinquent youth increases their likelihood of problem behavior. We test for analogous social contagion effects in the drug use and sexual behavior of college students, using data on the characteristics of first-year roommates to whom they were randomly assigned. We find that boys who reported binge drinking in high school drink much more in college if assigned a roommate who also binge drank in high school than if assigned a non-binge-drinking roommate. No such multiplier effect is observed for females, nor are multiplier effects observed for marijuana use or sexual behavior for either males or females. Students who did not engage in these behaviors in high school do not appear to be affected by their roommates' high school behavior.