The thesis aims to elucidate the factors which made it possible for the triumphant Bangalee nationalist movement expressed by the Awami League (AL) under the leadership of Mujib to fall from power and popular favour in the short space of three and half years. This entails some consideration of background features such as: Bangalee nationalism, the character of the AL, the legacies of the liberation war experience. Mainly, it calls for an inspection of the operations of various elements of the political system during the three and half years. The key element was the AL, dominant party from the moment of the emergence of the State. Therefore,· an examination of the AL and its affiliated organizations in the post-liberation period especially the working of the party at the local level had to be undertaken. The political system within which the AL functioned was in some degree one of its own making and attention therefore has to be given to the making (and changing) of the Constitution. At the same time, the AL though representative of the original nationalist movement, failed to win over the allegiance of all elements and thus opposition parties have to be examined to see what contributions they made to the direction of events. The bureaucracy becomes an important element in the polity during the three and half years and the army brings about the fall of the regime in 1975; the features of each of these institutions are set out in order to explain their roles. And finally an evaluation has been made of the performance of the government and its management of the various problems. The major findings of the study are as follows: Firstly, the factors antecedent to 1972 become manifest in the government and the party. Quite broad categories of people unaccustomed to administration shared the increasing expectations that were created by the nationalist movement especially in the course of the liberation war. But these expectations were disappointed. A period of total disillusionment followed due to the behaviour of those in power. Secondly, the disappointment of the people can not be attributed to any weakness that was inherent in Bangladesh. It can only be attributed to the failure of the ruling party. The actual conduct of the party and the government failed to mobilize and secure the support of the disillusioned. The AL which was a party of the urban middle class and the rural 'haves' found itself relying more heavily on certain richer peasants and did not seriously strive to cultivate the industrial workers. Thirdly, the AL was unable to exert political control. Its response and that of the government to popular resentment was expressed through the increasing use of force and strengthening of the institutions of force. This led to the isolation of the regime and it increasingly relied on the bureaucracy and the army. Thus an anomaly was created by drawing in the bureaucracy and the army into a system which had been designed as parliamentary democracy. The anomaly was removed by bringing about the fall of the regime and instituting direct military rule.