International Relations (IR) theory commonly holds security arguments as powerful instruments of political mobilization because they work to instill, circulate, and intensify popular fears over a threat to a community. Missing from this view is how security arguments often provoke a much wider range of emotional reactions, many of which frustrate and constrain state officials' attempts to frame issues as security problems. This dissertation offers a corrective by outlining a theory of the contentious politics of emotion and security. Drawing inspiration from a variety of different social theorists of emotion, including Goffman's interactionist sociology, this approach treats emotions as emerging from distinctive repertoires of social interaction. These emotions play a key role in enabling audiences to sort through the sound and noise of security discourse by indexing the significance of different events to our bodies. Yet popular emotions are rarely harmonious; they're socialized and circulated through a myriad of different pathways. Different repertoires of interaction in popular culture, public rituals, and memorialization leave audiences with different ways of feeling about putative threats. The result is mixed and contentious emotions which shape both opportunities and constraints for new security policies. The empirical purchase of this theory is illustrated with two cases drawn from the Canadian context: indigenous protest and the F-35 procurement. Both represent cases where attempts by state officials to frame an issue as a security problem were frustrated and constrained by a contentious politics of emotion. In the conclusion, I argue these findings should push IR theorists to adopt a more circumspect view of the mobilization of This was an emotional and contentious project. As much as I enjoyed writing it, there were periods wracked by serious doubt and uncertainty. Pulling me through these periods was an extensive community of friends, family, and colleagues. Carleton's Department of Political Science has been my home for the entirety of this project. It includes an exceptional group of faculty, students, and administrators-all of which work hard to make the Department a rich and creative home. I would like to thank the administrative staff, especially Brookes Fee, for consistently helping me navigate the University bureaucracy. I'd also like to thank the Department's faculty