In his address to the Fifth Conference of the Society of Muslim Brothers, held in Cairo in 1939, Hasan al-Banna declared: “We openly say that the Brotherhood is a political group and that its mission is a political one”. With this ended what one dissident called “the golden decade”. From 1939 onwards, the Brotherhood started a process whereby it gradually transformed itself from a religious revivalist movement to an organisation with decisively political objectives. This paper looks at the organizational history of the Muslim Brotherhood since 1973, and the reasons for its failure in the summer of 2013. Building on the literature of organisation and management studies, as well as pervious work in social movement theory, political sociology, political sciences and anthropology, the paper will analyse structural developments in the Brotherhood’s internal political organization in order to understand its rise and fall. Based on two years of fieldwork conducted in 2012 and 2013, and over 50 oral history interviews with Brotherhood leaders, rank-and-file members and dissidents, the goal is to provide a novel understanding of the Society’s history in the face of successive periods of rebuilding and reaction to the opening and closing down by the regime. In explaining the Brotherhood’s rise and fall, the paper will use the conceptual apparatus of the literature on organizational behaviour in order to creatively illuminate internal politics, decision-making, coalition building, as well as the indoctrination and mobilization of the rank-and-file apparatus. In particular, it will focus on the conflict between the so-called “Qutbists” (a label not used by the “Qutbists” themselves), who were in power during the period of governance from mid-2012 to mid-2013, and the “reformists”, who were pushed out of the organization during the Guidance Office elections of 2010. These camps did not distinguish themselves primarily in terms of religious doctrine, but rather in terms of their views on internal organisation, management and decision-making, with representatives of either side justifying strategic goals and priorities by shaping the Brotherhood’s ideology in a way that suited their specific political interests. The representatives of these coalitions were pitted against each other in personal and oftentimes acrimonious conflicts over the control over resources and key administrative positions. It will be argued that it is ultimately this internal clash of personalities that decisively weakened the Brotherhood on the eve of the revolution of 2011, thus being at the root of the Brotherhood’s failure in 2013.