ABSTRACT. Objective: Recruiting young adults for health research is challenging. Social media provides wide access to potential research participants. We evaluated the feasibility of recruiting students via free message postings on Facebook and Twitter to participate in a web-based brief intervention study. The sample comprised students attending U.S. and Canadian universities. Method: During three semesters, institutional review board-approved recruitment messages were posted in 281 Facebook groups, 7 Facebook pages, and 27 message "tweets" on Twitter.Results: A total of 708 eligible participants were recruited from Facebook. The mean enrollment rate per Facebook group was 0.21%; the rate was higher for host university groups (1.56%) compared with groups at other universities (0.10%). We recruited seven participants from Twitter. The sample was predominantly female (70%) with a mean age of 20.0 years. There were no signifi cant differences between host university participants recruited through social media and traditional methods. The web-based intervention completion rate was 65%, and participants from the host university were more likely to complete the intervention than were groups at other universities (p = .01). Conclusions: Social media provides access to a large number of potential participants, and social media recruitment may be useful to researchers who can harness this broad reach. Facebook recruitment was feasible and free and resulted in a large number of enrolled participants. Social media recruitment for researchers at their own universities may be particularly fruitful. Despite wide access to students with Twitter, recruitment was slow. Social media recruitment allowed us to extend web-based intervention access to students in the United States and Canada. (J. Stud. Alcohol Drugs, 76, 127-132, 2015)