Agenda 21 is a comprehensive plan of action to be taken globally, nationally, and locally by organizations of the United Nations System, Governments, and Major Groups in every area where humans impact the environment.

More than 178 governments adopted Agenda 21, the Rio Declaration on Environment and Development, and the Statement of Principles for the Sustainable Management of Forests at the United Nations Conference on Environment and Development (UNCED) held in Rio de Janeiro, Brazil, from June 3 to 14, 1992.

The Commission on Sustainable Development (CSD) was created in December 1992 to ensure effective follow-up of UNCED and to monitor and report on the implementation of the agreements at the local, national, regional, and international levels. It was agreed that a five-year review of Earth Summit progress would be made in 1997 by the United Nations General Assembly meeting in a special session.

The full implementation of Agenda 21, the Programme for Further Implementation of Agenda 21, and the Commitments to the Rio principles were strongly reaffirmed at the World Summit on Sustainable Development (WSSD) held in Johannesburg, South Africa from 26 August to 4 September 2002