What factors shape support for the human rights of prisoners and asylum seekers at the individual level? Although the human rights literature has expanded greatly in the last 30 years, comparatively little attention has been paid to (a) the many human rights outside of a very small set of physical or bodily integrity rights and (b) the role of public opinion. In this study, the authors build a theoretical model of various human rights as public opinion-related policy choices, developing the micro-foundations of public support for the human rights of vulnerable subpopulations. Drawing on the broader literature on public policy and international norms, they use experimental methods to test whether calls to rational effectiveness or international norm cascades improve support for the rights of prisoners and asylum seekers. Although they find baseline support for these rights in the United States and Canada, the findings also imply that rhetoric on the potential costs of human rights policy could reduce popular support, even when such policy is consistent with international norms.