This thesis successfully accomplishes two major aims. First, it explores the relationship between dehumanization, objectification, and men’s sexual aggression. Correlational and experimental results robustly support a role of dehumanization (particularly animalistic dehumanization), but not objectification, in men’s sexual aggression in an online context and when there is limited information about the potential target woman. However, evidence from this thesis does not point to a role of dehumanization or objectification in a more naturalistic (lab) setting, or when there is more than minimal information about a woman available to men. Secondly, we aimed to develop and validate a novel behavioral measure of men’s sexual aggression, the intrusive behavior paradigm. This methodology can be used to assess emerging manifestations of sexual aggression in the form of online behaviors specific to the digital age (otherwise known as technology-facilitated sexual aggression), as well as sexual aggression more generally. Results broadly support the use of this paradigm as representing a realistic and ecologically valid; practically effective and feasible; and ethically sound alternative that complements and expands on existing measures of men’s sexual aggression.