This paper examines the question of why so many ordinary Hutu participated in genocidal killing of Tutsi in Rwanda in 1994. I find that mass mobilisation was contingent on the fulfilment of two main conditions. Firstly it required a mindset – the internalisation of a set of historical and ideological beliefs – within the Hutu population. These were predominantly beliefs in a historical Hutu oppression at the hands of Tutsi and in an ideological definition of the ongoing civil war as an ethnic one, a Tutsi attempt to reinstate this historical order. Secondly, it required the commitment of State institutions to the genocidal project. This commitment provided the initial trigger, legitimacy and impunity for civilian participation in an anti-Tu...