Nurse practitioners (NPs) are increasingly called on to provide high-quality health-care particularly for people who face significant barriers to accessing services. Although discourses of social justice have become relatively common in nursing and health services literature, critical analyses of how NP roles articulate with social justice issues have received less attention. In this study, we examine the role of NPs from a critical social justice perspective. A critical social justice lens raises morally significant questions, for example, why certain individuals and groups bear a disproportionate burden of illness and suffering; what social conditions contribute to disparities in health and social status; and what social mandate NPs ought to develop in response to these realities. In our analysis, we draw on lessons learned from the initial Canadian experience with the introduction of NPs in the 1970s to consider the renewed and burgeoning interest in NPs in Canada, Australia and elsewhere. As we argue, a critical social justice perspective (in addition to the biomedical foci of NP practice) will be essential to sustaining long-term, socially responsive NP roles and achieving greater equity in health and health-care.