Armed non-state actors are involved in most armed conflicts today, yet international law provides few mechanisms to ensure that they comply with humanitarian norms applicable to them. In particular, monitoring and verification mechanisms that address the conduct of armed non-state actors rarely appear in multilateral treaties, and, even when they do, are weak and not applied in practice. Over the past few years, a number of alternative mechanisms have been developed to better monitor respect of humanitarian norms during internal armed conflicts and verify allegations of violations. This article examines the strength of these various mechanisms and then focuses on the Deed of Commitment, an innovative instrument developed by the Swiss-based non-governmental organization Geneva Call, to hold armed non-state actors accountable. Experience with the Deed of Commitment on the prohibition of anti-personnel mines shows that these alternative mechanisms can be effective in ensuring better compliance with at least some humanitarian norms.