Objective: To evaluate the efficacy of a stand-alone personalized normative feedback (PNF) intervention targeting misperceptions of gambling among college students. Participants: Undergraduates (N = 136; 55% male) who reported gambling in the past 30 days were recruited between September 2011 and March 2012. Methods: Using a randomized clinical trial design, participants were assigned to receive either PNF or an attention control task. In addition to self-report, this study used 2 computer-based risk tasks framed as "gambling opportunities" to assess cognitive and behavioral change at 1 week post intervention. Results: After 1 week, participants receiving PNF showed a marked decrease in perception of other students' gambling, and evinced lower risk-taking performance on 2 analog measures of gambling. Conclusions: Changes in both self-reported perceived norms and analog gambling behavior suggest that a single, stand-alone PNF intervention may modify gambling among college students. Whether it can impact gambling outside of the laboratory remains untested.