The influenza epidemic of 1978 was studied on a college campus, since a college is a type of "total institution" in which work, residence, and recreation are all concentrated in one organization with clearly delineated social boundaries and a unique social structure, A survey of a sample of 418 persons (378 students, 40 faculty members) revealed that more than 48 percent of the students contracted influenza and that the intersemester vacation was a social factor that may have aided in the disease's penetration of the institution's boundaries. The vacation exposed the students to the distase, and the resumption of classes allowed influenza to spread rapidly in the student population, which was concentrated within the boundaries of the educational institution. The faculty exhibited relative immunity to the disease compared with the students, having only a 5 percent attack rate. There were no significant differences in the incidence or duration of illness among the students by sex, year in school, residence area, floor of residence, fraternity or sorority membership, or participation in fraternity or sorority recruitment activities.