Objective. Young smokers commonly identify themselves as “social smokers,” a pattern of smoking behavior that is poorly understood. We assessed the prevalence and correlates of social smoking among US college students. Methods. Cross-sectional survey of a random sample of 10 904 students enrolled at 119 nationally representative US colleges in 2001. Results. A total of 51% of 2401 current (past 30-day) smokers were social smokers. (To assess social smoking, students were asked, “In the past 30 days, do you smoke mainly when you are with people, mainly when you are alone, or do you smoke as often by yourself as with others?” Students who stated that they smoked mainly with others rather than alone or equally by themselves and others were defined as social smokers for this analysis.) Social smoking was independently associated with a lower frequency and intensity of tobacco use, less nicotine dependence, less intention to quit, and fewer recent quit attempts. Conclusions. Social smoking is a distinct pattern of tobacco use that is common among college students and may represent a stage in the uptake of smoking.