This article presents an empirical study of six grievance mechanisms in multi-stakeholder initiatives (MSIs). It argues that key characteristics of each grievance mechanism as well as the contexts in which they operate significantly affect human rights outcomes. However, even the most successful mechanisms only manage to produce remedies in particular types of cases and contexts. The research also finds that it is prohibitively difficult to determine whether ‘effective’ remedy has been achieved in individual cases. Furthermore, the key intervention by the UN Guiding Principles on Business and Human Rights (UNGPs), to prescribe a set of effectiveness criteria for designing or revising MSI grievance mechanisms, itself appears ineffective in stimulating better outcomes for rights-holders. Drawing on these findings, the article reflects on the future potential and limitations of MSI grievance mechanisms within broader struggles to ensure business respect for human rights.