Bystander intervention is a potentially potent tool in the primary prevention of sexual assault but more information is needed to guide prevention programs (Banyard 2008). Undergraduates (378 women and 210 men, primarily White) at a central coast California university completed an anonymous questionnaire measuring five barriers identified by the situational model of bystander intervention (Latane and Darley 1970) and bystander intervention behavior. As expected, the barriers were negatively correlated with intervention, were greater for men than for women, and intervention likelihood was affected by perceptions of victim worthiness, especially for men. Hypotheses predicting a positive relationship between having a relationship with the potential victim or perpetrator and intervention were supported. Implications for sexual assault bystander intervention programming are provided.