On one hand, NGOs are seen as experts because of their proximity to the problems they address. They provide knowledge relevant to the solution of these problems and can bring this into the political process. They are able to increase the efficiency of global governance by participating in the policy-formation processes of international organizations. In this paper I will explain the role and functions of NGOs as described in the debate about their legitimacy and theorize – while applying Ernst Haas's theory of organizational learning – on the mechanisms likely to lead to their increasing integration into international institutions as well as the implications of this integration.