The thesis focuses on three main questions: the quality of democracy, democratic backsliding, political culture, and the relationship among them. The theoretical basis of the thesis starts with the quality of democracy model of Larry Diamond and Leonardo Morlino. The theoretical purpose of the research is to reconceptualise the quality of democracy and embed it into political culture to find answers to democratic stagnation and backsliding experienced in European states today. To achieve this objective, the thesis offers a four-level model of political culture that provides a foundation for explaining the links among different aspects of political culture and factors of democratic quality. Additionally, the thesis proposes a two-fold hierarchical interpretation of the factors of the quality of democracy to define the deficiency needs of democratic functioning. The main hypotheses cover the connections among the three factors mentioned above. The first hypothesis focuses on the continuity and fragmentation of political culture as explanatory factors that play a crucial role in the thesis. The second hypothesis examines the ‘citizen dimension’ of democratic quality and its impact on democratic stability through factors such as the citizens’ interest in the political dynamics of their own country, their perceptions of their democracy, and their confidence in democratic institutions. The third hypothesis investigates the potential reasons and levels of democratic stagnation and backsliding in democracies, arguing that political culture and the weakening of the rule of law are the main influencing factors, as the latter serves as the basis and guarantee for the other factors of the quality of democracy. The empirical research is based on a comparative analysis of the quality of democracy in three European countries with fundamentally different democratic systems and traditions of democratic evolution: Luxembourg, the UK, and Hungary. The methodology used is based on the most-different cases with similar results model.