Public attitudes related to social Europe are important for legitimating the aspirations of the European Union and European politicians to deepen European integration. This paper investigates public opinion about social Europe by analyzing attitudes related to the basic principles for European social security measures and attitudes about implementing a uniform European social security system. Based on a survey conducted in 13 European countries, it explores the discrepancies between the two interrelated phenomena and investigates in detail the factors responsible for the strong support for general principles, but fizzling support for the implementation of a European social system. The main findings demonstrate that the value-based mechanisms are primarily responsible for carrying over the positive attitudes towards the general principles to positive attitudes towards a uniform European social security system. In contrast, self-interest does not play a prominent role. Left-leaning individuals, emphasizing the justice principle of need and who identify and trust the European Union are the primary proponents of general principles related to social Europe, as well as for the potential realization of a uniform European welfare system