This chapter examines the role of non-governmental organizations (NGOs) in advancing international criminal justice. I argue that NGOs have had considerable impact by contributing, among other things, to the global struggle against impunity through advocacy for the creation of more robust institutional mechanisms to prosecute those who perpetrate such crimes. This ranges from supporting the processes that led to the creation of several ad hoc international tribunals for Yugoslavia, Rwanda and Sierra Leone, all the way through to the establishment of an independent permanent international penal court based in The Hague. The crux of my claim is that a historically sensitive approach to evaluating the role of NGOs in international governance shows that these entities are not only willing, but also capable of enhancing the protection of human rights and international criminal justice especially but not exclusively in less developed regions of the world.