Grounded in self-determination theory (Deci & Ryan, 1985, 2000) and objectification theory (Fredrickson & Roberts, 1997), the purpose of this thesis was to investigate the role of dispositional autonomous and controlled motivation in predicting who might be more protected from or more vulnerable to experiencing state self-objectification (Manuscript 1), diminished cognitive functioning or cognitive performance (Manuscript 1 & 2), and poorer self-evaluations (Manuscript 2) following exposure to advertisements portraying one of two leading cultural body ideals: the male muscular ideal (Manuscript 1) or female thin ideal (Manuscript 2). The objectives were to investigate the effects of the two ideals while evaluating the contribution of autonomous and controlled motivation orientation in statistically predicting various body image consequences using five separate male undergraduate samples. Consistent with the overall hypotheses of the thesis, the muscular ideal video and thin ideal video significantly decreased men’s cognitive functioning and cognitive performance compared to men in the neutral video conditions (Manuscript 1 & 2). In addition, men who were primed with the muscular ideal video demonstrated significantly higher levels of self-objectification compared to those in the neutral condition (Manuscript 1: Study 1 and Study 2). Mediation results revealed an indirect effect of the muscular ideal video on men’s cognitive functioning (i.e., appearance schema activation) through self-objectification (Manuscript 1: Study 1), thereby supporting objectification theory as a means of explaining how portrayals of muscular body ideals affect men’s cognitive function. However, inconsistent with previous studies, the female thin ideal did not significantly affect men’s self-evaluations (Manuscript 2: Study 2). Lastly, in line with self-determination theory, all five studies (Manuscript 1 & 2) found that autonomous motivation orientation played a significant moderating role against the cognitive consequences associated with cultural body ideals among young college men. Men who viewed the muscular ideal video and who reported high levels of dispositional autonomous motivation demonstrated less appearance schema activation, less difficulty solving a challenging Soma puzzle, and performed better on the Modified Stroop task compared to men with low levels of dispositional autonomous motivation (Manuscript 1). Similarly, men who reported high levels of dispositional autonomous motivation and viewed the thin ideal also demonstrated less appearance schema activation and less difficulty solving a challenging Soma puzzle compared to men who reported low levels of dispositional autonomous motivation (Manuscript 2). In contrast, controlled motivation orientation was not a significant moderator across all five studies (Manuscript 1 & 2). Collectively, our findings highlight the importance of incorporating autonomous motivation orientation and self-objectification into theoretical models of men’s body image.