The dissertation project explores how the International Labour Organization’s (ILO) moral authority affects the organization’s reaction to being challenged and having its norms and institutions contested. Having the constitutional capacity to create legally binding international norms, the ILO needs to perform a balancing act between meeting its purpose, demands by its constituents and adapting to events and changing circumstances in its environment. Against this background, two different examples of contestation of the ILO’s norms and institutions are examined: 1) The right to strike conflict and the deadlock at the 2012 International Labour Conference 2) The gridlock regarding Global Supply Chain governance. The dissertation draws on ideas from sociological neo-institutionalism and organizational learning to argue that the ILO constructs and uses its moral authority as a means of countering contestation to maintain its legitimacy and position in world society. The weight of moral authority and moral communication is used by the ILO constituents to achieve their goals when they cannot refer solely to the ILO’s rational-legal source of authority. The main research question guiding this dissertation project is therefore concerned with how moral authority is constructed and applied by the ILO to counter contestation of its norms and institutions.