Title VII prohibits sex discrimination in the workplace “because of sex.” Once on the job, however, courts allow employers to impose trait discrimination policies on employees, including sex stereotypical ones. Based on a survey experiment, we found that sex stereotyped dress styles for women—defined by bright colors, long hair, excessive make-up in contrast to dark suits, ties, and short hair cuts for men—sexualize women, thereby undermining viewers' perception of women's professional competence. A vast social-psychological literature explains “why.” Specifically, gender is a diffuse status characteristic that generally diminishes the perception of women’s capabilities. Sexualized dress styles augment that effect of gender by diverting viewers' attention from women's job performance to the visual attributes of women as objects. Our study confirms that women’s sexualized dress styles decrease viewers’ perceptions of women’s competence. We contend that this reduction in the perception of women’s competence disproportionately disadvantages members of a protected class, women, and, by so doing, constitutes an “adverse effect”. Notably, Title VII prohibits policies that impose adverse effects. Thus, by integrating legal standards with social psychological scholarship, this study presents a new foundation for the claim many legal scholars have sought to make, namely, why at least some trait discrimination policies violate Title VII.