Of the estimated 214 million people who have migrated from poorer to richer countries in search of a better life, between 20 and 30 million have migrated on an unauthorized, or “illegal,” basis. All have health needs, or will in the future, yet most are denied health care available to citizens and authorized residents. To many, unauthorized im/migrants’ exclusion intuitively “makes sense.” As scholars of health, social justice, and human rights, we find this logic deeply flawed and are committed to advancing a constructive program of engaged critique. In this commentary, we call on medical anthropologists to claim an active role in reframing scholarly and public debate about this pressing global health issue. We outline four key theoretical issues and five action steps that will help us sharpen our research agenda and translate ourselves for colleagues in partner disciplines and for broader audiences engaged in policymaking, politics, public health, and clinical practice. [unauthorized im/migration, “illegality,” social determinants of health, “deservingness,” public anthropology]