The number of Commissions of Inquiry (CoI or CoIs), especially those established by the UN, has increased significantly over the last years. Such bodies may refer to and apply various norms of IHL. Based on examples derived from the practice of different CoIs, this contribution considers how they may strengthen respect for this body of law. This may be achieved by elucidating allegations of violations, addressing controversial behaviour on the battlefield, clarifying the contents and interpretation of norms, and providing a basis for criminal prosecutions. However, significant challenges stand in the way of realising this potential, including one-sided mandates, the information and evidence available, IHL expertise, and the relationship with International Criminal Law. The value of CoIs should consequently not be overstated.