Although transparency is frequently employed to enhance the legitimacy of public organizations, several scholars point to its potentially negative implications. This study analyzes the impact of transparency on the authority of peer reviews in international organizations. Authority, here conceived as rooted in legitimacy beliefs, is crucial for peer reviews to produce effects. This research is based on results from an online survey and forty-three interviews with actors involved in two United Nations peer reviews: the Universal Periodic Review in human rights and the Implementation Review Mechanism in the fight against corruption. The article shows that transparency positively affects the perceived development of pressure, yet negatively influences mutual learning and appears to be unable to ensure equal treatment of states.