Christian Democratic socio-economic ideology underwent a paradigm shift through the Europeanization of its party networks. Christian Democratic networks started with a distinctive Catholic socio-economic ideology emphasizing corporatism, welfare transfers and a coordination of the economy. This institutional blueprint influenced the early years of European socio-economic integration. The original social Catholicism was gradually replaced by Protestant and secular inspired socio-economic ideology, emphasizing undistorted market competition with successive enlargements of the European Union and the European Peopleâs Party (EPP). The article empirically reconstructs the contested process of transformation of the EPPs socio economic ideology through the inclusion of mainstream conservative and Protestant Christian Democratic parties and its impact on European Christian Democracy and the European integration process.