"15 Global Challenges" have been defined and tracked since 1997 by The Millennium Project of the American Council for the United Nations University, in its State of the Future series of annual reports. The challenges were defined by the Project's Global Outlook Panel through modified Delphi method questionnaires, and are updated annually. The material exists in several languages and the inputs have come from the project's twenty-two nodes around the world. The descriptions of each challenge include a review of the current state of affairs, approaches to address the challenge, and regional perspectives.