This chapter analyses two aspects of public intervention aimed at increasing collaboration between agents of innovation. It addresses the case of university-business relationships, and then considers public agencies, as illustrated through the example of space agencies. Public intervention in research and innovation activities has been analysed greatly in neoclassical economics. It is justified in a context of market failure theory which suggests possible solutions to private underinvestment. According to the national innovation systems school, innovation is an interactive process that is favoured by the relationships between innovative agents. Although collaboration is required between private agents and institutions, it requires trust and, to some extent, common habits and mindsets. Effective collaboration requires social capital. The effectiveness of an entire national system of innovation requires greater collaboration between universities and industry which have different goals and cultures. The concept of collaboration gives rise to much discussion in economic theory, the risk of 'betrayal' in a network being the classical problem.