The last thirty years have seen a clear trend in devolution of responsibility for social protection from the State to the private sector. However, the pure form of privatisation, i.e., the absence of any public action in the field of social security, is quite marginal. More widespread are different degrees of ‘functional’ privatization in a framework where networks of multiple welfare providers compete in ‘quasi-markets’. Therefore, the public-private divide should not be conceived anymore in terms of binary logic: There is not a dichotomy, but rather a continuum along the public-private axis. However, the private and public tiers of social security are not functionally equivalent. For instance, only a public, PAYG system can fulfill a redistribution function. Still, at least from the viewpoint of a human rights approach, the most significant danger of unbalanced privatisation is its impact on the protection of social security as a right of social citizenship. A recognition of the normative content of the social right to social security as a fundamental constitutional right is, in this sense, a prerequisite for social citizenship.