Based on the observation that some Central and Eastern European (CEE) EU member states have developed into stable democracies, while others are experiencing democratic backsliding, which has important implications for the role of the EU as a promoter and guardian of democracy, this thesis aims to understand this development. To this end, it examines the impact of various theory-driven determinants from the dimensions of political culture, economic factors, governance quality and socio-political dynamics on democratic backsliding in CEEEU member states. Based on panel data from 11 countries for the period 2000-2021, mainly provided by V-Dem, the World Values Survey, the European Values Survey and the World Bank, the relationship is analysed using pooled logistic regression in a stepwise manner with the aim of obtaining a final model that best explains democratic backsliding. A first conducted descriptive analysis identifies five cases of backsliding: Hungary (2010-2021) and Poland (2015-2021) show the sharpest declines, while Croatia (2013-2021) and the Czech Republic (2013-2021) represent milder cases, with Slovenia (2012-2021) falling somewhere in between. A common pattern of backsliding was found regarding the aspects of democracy affected, as well as a pattern in terms of enabling conditions and factors. The results suggest that democratic backsliding is more likely in countries with weak economic performance, low levels of political trust (especially in the EU) and high polarisation. Contrary to theoretical assumptions, the results also reveal that high levels of support for democracy and state capacity increase the likelihood of democratic backsliding.