The discussion on welfare state in social sciences has been constantly developing since the Second World War. Up to the 1980s, the literature mainly followed a socio-historical perspective, trying to understand the conditions (economical, political, institutional, etc.) that had triggered the development of these national systems to provide collective protection against the risks of life. Such a perspective tended to blur national differences, which were mainly understood in terms of forerunners versus latecomers. During the 1980s and 1990s, in parallel with the construction of Europe, the main focus was on understanding these national differences. Looking more closely at these national systems led to the construction of typologies. With the turn of the 21st Century, the main questions now concern understanding the processes of change. In this chapter, we review some of the key contributions to this debate, which aims at providing an insight into the reforms of welfare states during the last decades in Europe.