Change in Eastern Europe and the Soviet Union presents a whole new set of sociological problems, requiring a revision of old theories of large-scale institutional change. My aim in this paper is to delineate patterns and gaps to be found in sociological theories dealing with change in Soviet-type societies. After a short review of the explanatory claims of totalitarian, modernisation, civil society and institutional perspectives, I propose an analysis of such change in terms of the strategic conduct of the main agents (the state-party and society) within its institutional context. The collapse of communism is seen as a result of the evolution of the system caused by the lack of institutional arrangements which could set limits to the party- state's arbitrary rule, and -- by the same token -- could create conditions for economic efficiency and encourage the emergence of interests other than those directly serving the centre. This can be seen as a spiral process of change in which the system was long losing its internal consistency and gradually exhausting itself. This process consisted of two mutually reinforcing trends: first, changes in the relationship between political centre and society, resulting in the declining ability of the party-state to act effectively as the agent of society; secondly, the growing heterogeneity and internationalisation of society, leading to the growing incompatibility of central planning with the informational and motivational requirements of a modern economy., Four Theories of State Socialism Recent change in Eastern Europe as the biggest political upheaval of the last forty years poses a particular challenge to contemporary political and social theory. [...]