The Economic Community of West African States (ECOWAS; also known as CEDEAO in French and Portuguese) is a regional political and economic union of fifteen countries located in West Africa. Collectively, these countries comprise an area of 5,114,162 km² (1,974,589 sq mi), and in 2015 had an estimated population of over 349 million.

Considered one of the pillar regional blocs of the continent-wide African Economic Community (AEC), the stated goal of ECOWAS is to achieve "collective self-sufficiency" for its member states by creating a single large trade bloc by building a full economic and trading union. The union was established on 28 May 1975, with the signing of the Treaty of Lagos, with its stated mission to promote economic integration across the region. A revised version of the treaty was agreed and signed on 24 July 1993 in Cotonou.

The ECOWAS also serves as a peacekeeping force in the region, with member states occasionally sending joint military forces to intervene in the bloc's member countries at times of political instability and unrest.