This article provides a rationale for "assessment for social justice", through which a greater focus is given to the role of assessment in achieving the social justice aspirations of higher education. It takes inspiration from work on assessment for learning to propose that as assessment is a powerful driver of how and what students learn, we should also consider its potential to drive a commitment for greater social justice within and through higher education. The article provides a critique of procedural notions of social justice, which I argue have implicitly influenced current notions of fairness in assessment. Greater reflection on the possible flaws in such procedural notions is a starting point for rethinking assessment in social justice terms. I then draw on two alternative conceptualisations of social justice--the capabilities approach and critical theory--to consider the ways in which key assessment issues would look differently through these alternative lenses. The article does not aim to establish a prescriptive list of practices around the notion of assessment for social justice, but rather upon debate and a greater appreciation of the implications of how we conceptualise justice and the attendant influence on what may be considered appropriate assessment policies and practices.