At a more concrete level, the chapter explores the concept of political systems. It also discusses, what is necessary at this level, other developmental trends in other dimensions, which have a direct impact on modern political regimes. The elements of political regimes are identified, models for the analysis proposed and the sources of legitimacy detailed. Autocratic, oligarchic and democracy regimes are analysed, with special attention to the contemporary model of advanced liberal oligarchy, which may be displacing liberal democracy. Dahl, Linz, Santos and other contemporary writers have pride of place in the chapter. It ends with a critical discussion of the notion of ‘populism’, in particular, but not only, with reference to Laclau’s formulation.