Institutionalized complaint systems are notable features of improving public programmes and government practice. This article reviews literature on formal grievance redress mechanisms in the global South to understand whether these mechanisms help the aggrieved to complain and seek redress for their grievances. In this emerging literature, the institutional and definitional boundaries of formal grievance mechanisms are slippery; systems that look like grievance systems may do little to enable complaints by those who seek to register them, and even less to enable them to achieve redress; with limited evidence on how these formal grievance systems work on the ground, and without sufficient power to act on complaints these formal grievance systems appear to be more ornamental; and where they have worked uncommonly well they have not always attracted political support to go to scale. The article concludes with a discussion of avenues for research identified through this literature review.