The United Nations Conference on Sustainable Development, held in June 2012 in Rio de Janeiro, was probably the largest event in a long series of mega-summits on environmental protection and sustainable development. Roughly 44000 participants descended on Rio de Janeiro to take part in ten days of preparatory committee meetings, informal consultations, side events, and the actual conference. Yet despite this unprecedented high attendance by participants from governments and civil society, the outcome of the conference is less than what many had hoped for. In this paper, I review the outcomes of the 2012 Rio Conference in detail, with a special focus on its contributions towards the reform of the institutional framework for sustainable development. Following this review, I discuss the way ahead, including whether mega-conferences will continue to play a major role in the governance of our planet.