Objective: The authors examined the sociodemographics and psychobehavioral characteristics of undergraduate US college students who abstain from alcohol. Participants: The respondents were 5,210 undergraduates from 32 colleges and universities. Methods: A survey was mailed to 300 randomly selected students per institution (spring 2000 or 2001). The response rate was 56.2%. Results: Overall, 20.5% of the students abstained. Predictors of abstention included the student's own negative attitude toward alcohol use; perception of friends' alcohol attitudes; male gender; being under age 21; abstaining in high school; non-Greek member or pledge; nonathlete; nonsmoker; non-marijuana user; participant in a religious group; working either 0 or 10+ hours per week for salary; having a mother who abstains; and having a close friend who abstains. Conclusion: Additional research on abstainers is warranted. Campus-based prevention programs should be grounded in a better understanding of how motives not to drink are developed and sustained in high school and college. (Contains 6 tables.)