The institutionalisation of Fatah mirrors the evolution of the PLO and the Palestinian national cause generally. Understanding the factors that have influenced Fatah's politics of violence, and its political path -- and the balance between the two -- help to explain the political history of the Middle East in recent decades. Fatah's institutionalisation is marked by alternating bases of the organisation's legitimacy: organisational, communal, and external. Transformations from one phase to another are distinguished by the shifts in relative importance assigned to the different sources of legitimacy, which in turn dictated different courses of action for the organisation.