Research Question: Anger is believed to be a powerful motivator of group mobilization. The objective of this dissertation is to examine the role of anger in assisting individuals to overcome the collective action problem. Theory: I utilize Intergroup Emotional Theory in order to build and test hypotheses on when and how anger will lead to mobilization. Methods: I test my hypotheses through four experiments. Experiment 1 examines how individual level anger impacts mobilization. In Experiment 2, I implement a test to induce anger towards an out-group. In Experiment 3, I then examine how anger towards an out-group impacts mobilization under the contexts of threat and competition. In Experiment 4, I look at different threatening contexts and how anger towards an out-group, limited information, and discrimination all work together to impact mobilization. Results: In Experiment 1, I found that when an angry subject is asked to take action in a task unrelated to that anger, the subject fails to mobilize. In Experiment 2, I built and tested two experimental manipulations of out-group anger and was successful in inducing anger directed towards an out-group. Having successfully induced out-group anger, Experiment 3 then demonstrated that out-group anger increases mobilization under competition, but not under threat. The mobilizing effects of out-group anger was limited under threat because subjects also felt angry towards their own in-group. Lastly, I reexamine different variations of threat on mobilization. I attempt to reduce increases in in-group anger by limiting information and discriminating against the angry group, but as I stack the deck against the angry group, they responded by mobilizing less. Conclusions: The potential for anger to mobilize may be contingent upon the level of out-group and in-group anger within a group. These findings collectively shed light on how out-group anger can either facilitate action or lead to inaction.