The approach of the legal segmentation as a form of regulation of social policy is extended towards a sociological institutionalist thinking. In order to differentiate the scope of social mechanisms and possible fields relevant for labour regulation, we propose five social institutions as norms of action and mechanisms that structure labour and its regulation: social networks, professions, markets, organisations and public regimes. Like all formalised law, this social-institutional embedding of labour regulation and its segmented character can be understood as the sedimented outcome of economic, political, cultural and social interests, struggles and power relations over time. Concluding reflections show how the proposed multi-level and multi-dimensional approach to cross-border labour regulation might relate to the approach of coverage and generosity of formal labour regulation and protection as an important element of global social policy.