The Local Agenda 21 (LA21) Campaign promotes a participatory, long-term, strategic planning process that helps municipalities identify local sustainability priorities and implement long-term action plans. It supports good local governance and mobilizes local governments and their citizens to undertake such multi-stakeholder process. The LA21 process leads to the preparation and implementation of a long-term, strategic plan that addresses priority local sustainable development concerns.

The development of Local Agenda 21 and its subsequent endorsement at the Rio Earth Summit as Chapter 28 of Agenda 21. A 2002 survey found that more than 6,400 local governments in 113 countries have become involved in LA21 activities over a 10-year period. Through LA21, local governments are establishing stakeholder groups, developing local sustainability plans and acting on these plans.