The goal of this study was to examine the costs associated with witnessing the sexual harassment of a male colleague. More specifically, we investigate (a) whether observed male gender harassment is related to psychological and physical health, and negative and positive job-related behaviors and attitudes, and (b) the mediating roles of discrete negative emotions (anger, fear) and identity-based evaluations (collective self-esteem). We explore these questions in a sample of men and women employed in "blue collar" professions. Our results show that the relationships between observed male gender harassment and psychological and physical health symptoms, withdrawal and workplace deviance, and affective commitment, were indirect and mediated via witness anger. Moreover, witnessing the gender harassment of a male colleague was also indirectly related to workplace deviance via collective self-esteem among women. Implications for theory, research, and practice are considered.