In the approach to the World Summit on Sustainable Development, being held in Johannesburg from late August through early September, United Nations Secretary-General Kofi A. Annan prepared an address for the American Museum of Natural History's annual environmental lecture. Annan emphasizes five sustainable development priorities for which concrete results are both essential and achievable: water and sanitation, biodiversity and ecosystem management, energy, agricultural productivity, and health. An edited version of the speech, delivered by Mrs. Nane Annan in New York on 14 May 2002, appears on the following pages.