This article critically reviews social science research relevant to lay people defining sexual harassment, including research on what behaviors are considered harassing, the effects of harasser status on perceptions of harassment, and gender differences in definitions of sexual harassment. Included in this review are data from a previously unpublished study of definitions of sexual harassment among a sample of over 4000 students, faculty, and staff at the University of Minnesota. Our review suggests that there is now quite a bit of lay consensus regarding which categories of behaviors are generally considered harassing. Studies on both the effects of harasser status and gender differences in perceptions of harassing behaviors are less consistent. We conclude our review with several recommendations for increasing the external validity of this research.