Individuals are an integral part of international human rights. While central to our leading theories of human rights change and to the efforts of human rights organizations in the real world, empirical scholarship has not systematically investigated how individuals choose to become advocates. Without the mobilization of individuals, human rights institutions and campaigns are deprived of the energy and material that fuel their success. In this dissertation, I closely evaluate the reasons why individuals choose to become engaged in human rights campaigns, what drives them to advocacy, and what this tells us about the relationship between political psychology and international human rights. In Chapter 1, I consider how incidental emotions influence individuals’ support for child hunger relief and refugee assistance, finding that negative emotions like disgust tend to amplify pre-existing views. In Chapter 2, I evaluate the effects of the negativity bias and loss-aversion bias on support for child hunger relief. I find that the combination of negative imagery and gains-focused messaging had a significant and positive effect on individuals’ support for both personal and government action to help feed and house the hungry. In Chapter 3, I discuss the important effects that political ideology had on the relationships I observed in Chapters 1 and 2. I illustrate how those on the political left and right responded in systematically different ways in each of the experiments, and note how these differences reveal the critical importance of targeted messaging with an emphasis on ideology. Finally, I conclude with a discussion of these dissertation findings as theoretically important and practically useful, with an emphasis on a focused and practically-oriented future research agenda.