This chapter focuses on the 1992 United Nations Conference on Environment and Development (UNCED), the Rio “Earth Summit.” It shows how, despite incentives to address institutional dysfunction and mounting global environmental problems by institutionalizing sustainable development within the United Nations system, divergent expectations persisted until momentum built toward UNCED. The Rio conference, which marked the twentieth anniversary of the 1972 Stockholm conference, emerged as a Temporal Focal Point in United Nations environmental politics. Convergent expectations triggered a significant increase in political and analytical investments in change processes from state and non-state actors, leading to a transformation of the informational and political context. These investments produced significant institutional change, including the creation of the Commission on Sustainable Development (CSD) and the institutionalization of the World Bank-operated Global Environment Facility. States also launched the United Nations Framework Convention on Climate Change, the Convention on Biological Diversity, a set of Forest Principles, and the United Nations Convention to Combat Desertification.