Higher education institutions are increasingly aware of the importance of inclusive assessment, yet large-scale implementations of inclusive assessment policies and practices are rare. Why is it so tricky to design assessment that inclusively considers the diversity of students? This article argues that whilst trying to solve the problem of inclusive assessment, research and practice communities may have forgotten to pay attention to this problematisation itself. Perhaps the problem of inclusive assessment cannot be solved. In this article, inclusive assessment is theorised as a "paradox" that is organised around three central tensions: (1) Whereas assessment aims to reduce human diversity to hierarchies and categories, inclusive education seeks to move beyond such sorting systems; (2) whereas assessment relies on uniformity, inclusion builds on diversity; (3) whereas assessment is grounded in individualism, inclusion grows from interdependence. Inclusion and assessment may simply be incompatible, at least in terms of how these ideas are currently understood. It is suggested that higher education sectors may continue living with the paradox, try to mitigate the paradox, or embrace the paradox. Given that students are the ones who must live through this paradox, these issues are not merely theoretical but urgent and real.