The basic assumption of this article is the recognition that the complexity of the challenges related to population ageing forces the development of cooperative relations between public policy entities representing various sectors. In other words, more intense and better-coordinated cooperation is needed between the public sector, commercial sector, non-governmental sector, informal sector, and sector of social economy entities (e.g., cooperatives). In this context, the implementation of the assumptions of the theories of governance, co-production, and a mixed economy of welfare (in other words: multi-sectoral social policy) is of fundamental importance. As a consequence, the article points to selected threads of the discourse on the relationship of population ageing with social entrepreneurship and social innovation. The text also cites examples of best practices and initiatives in the area of the social economy. The summary includes recommendations for public policy entities and proposed directions for further research.