This paper explores the sources of legitimacy of regional governance networks and pays special attention to the aspect of credibility. We argue that legitimacy of regional governance networks is not only based on legality, justifiability, and consent, but also on the ability of the regional governance network to gain credibility in the shadow of hierarchical decision making. Credibility has not received the same degree of attention as other aspects of legitimacy. However, networked forms of governing – such as regional governance – to a large extent rely on the belief held by participating governmental actors and higher levels of government in this type of collaboration and governing. They must be convinced of the added value of this type of collaboration. We empirically illustrate the importance of credibility as an aspect of legitimacy, using two examples of cases of regional housing governance in the Netherlands.