The thesis examined the case of organizational and ideological transformation of the Bulgarian Socialist Party (BSP) and its adaptation to the democratic political system after the collapse of communism in 1989. As a specific example of former communist party, which had to retain, rather than regain public support, the study investigated specifically the main incentives of those processes. This aim involved the application of qualitative approach, based on existing academic theories and empirical research of primary and secondary document sources.The research firstly established that the specific development of Bulgarian democracy and the initial place of BSP in it depend on the historical legacies from the particular communist regime. Based on this suggestion, the thesis determined secondly that the Bulgarian democratic political system outlines the changing specific conditions to which the party adapts. In this respect the particular electoral performance highlights the incentives and outcomes for party transformation and successful adaptation. The decisions of the particular party elite shape the specific trajectory of transformation, while the specific elite resources of the party determine the level of success for its implementation.In this context the thesis argued that BSP is a case of ideological and organizational degradation, as the initial electoral success of the party eliminated the internal drives for fundamental transformation. The balancing adaptation strategy of the party shaped an incoherent, rather populist ideological profile, as the party developed clientelist organizational characteristics. Therefore, the prospects for long-term electoral success of the party are rather declining.The results confirmed that the internal party resources and decisions are decisive for the transformation and adaptation of a political party. Contrary to the original theory, the thesis suggests that the specific country context, embodied by the environmental factors, presents a particular framework, which to large extent guides those choices. Therefore, set in different circumstances the factors, influencing the transformation and adaptation of communist successor parties, have varying relevance. Furthermore, the thesis established the importance for further research and empirical measurement of clientelism as significant factor, which influences political processes.

The thesis examined the case of organizational and ideological transformation of the Bulgarian Socialist Party (BSP) and its adaptation to the democratic political system after the collapse of communism in 1989. As a specific example of former communist party, which had to retain, rather than regain public support, the study investigated specifically the main incentives of those processes. This aim involved the application of qualitative approach, based on existing academic theories and empirical research of primary and secondary document sources.The research firstly established that the specific development of Bulgarian democracy and the initial place of BSP in it depend on the historical legacies from the particular communist regime. Based on this suggestion, the thesis determined secondly that the Bulgarian democratic political system outlines the changing specific conditions to which the party adapts. In this respect the particular electoral performance highlights the incentives and outcomes for party transformation and successful adaptation. The decisions of the particular party elite shape the specific trajectory of transformation, while the specific elite resources of the party determine the level of success for its implementation.In this context the thesis argued that BSP is a case of ideological and organizational degradation, as the initial electoral success of the party eliminated the internal drives for fundamental transformation. The balancing adaptation strategy of the party shaped an incoherent, rather populist ideological profile, as the party developed clientelist organizational characteristics. Therefore, the prospects for long-term electoral success of the party are rather declining.The results confirmed that the internal party resources and decisions are decisive for the transformation and adaptation of a political party. Contrary to the original theory, the thesis suggests that the specific country context, embodied by the environmental factors, presents a particular framework, which to large extent guides those choices. Therefore, set in different circumstances the factors, influencing the transformation and adaptation of communist successor parties, have varying relevance. Furthermore, the thesis established the importance for further research and empirical measurement of clientelism as significant factor, which influences political processes.