This policy study examines the supposed radicalisation within mainstream right parties and its implications for the broader political landscape, notably for (social) democracy. Central to this inquiry is a comprehensive analysis of the extent to which mainstream right parties have embraced more extreme positions and the resulting ramifications. Through a comparative lens, this study delves into the evolving positions of different mainstream right-wing party families – Christian democrats, conservatives and liberals – alongside those of the populist radical right and social democracy across Western Europe.