Objectives: To examine the impact of downward social comparison and the "known partner is a safe partner" heuristic on college students' sexual decisions. Participants: One hundred-eighty heterosexual or bisexual undergraduate college students. Methods: Participants read dating vignettes that varied on perspective and familiarity and then rated the likelihood the couple would engage in sexual intercourse and use a condom. Results: There were no differences in rated likelihood based on familiarity, suggesting that the students did not view the 2 partner types as significantly different. Students rated the likelihood of sexual intercourse lower and condom use higher when the vignette was presented from the second person perspective. Conclusions: The students' use of downward social comparison is consistent with the "better than average effect," suggesting that the students perceive their own behavior as safe. The implication is that safer sex messages might be most effective if they focus on what students will gain by practicing safer sex behaviors, not just avoidance of a risk behavior. (Contains 2 tables.)