The Organisation for Economic Co-operation and Development (OECD, French: Organisation de coopération et de développement économiques, OCDE) is an international economic organisation of 34 countries founded in 1961 to stimulate economic progress and world trade. It is a forum of countries committed to democracy and the market economy, providing a platform to compare policy experiences, seek answers to common problems, identify good practices, and co-ordinate domestic and international policies of its members.

The OECD originated in 1948 as the Organisation for European Economic Co-operation (OEEC), led by Robert Marjolin of France, to help administer the Marshall Plan for the reconstruction of Europe after World War II. Later, its membership was extended to non-European states. In 1961, it was reformed into the Organisation for Economic Co-operation and Development by the Convention on the Organisation for Economic Co-operation and Development. Most OECD members are high-income economies with a "very high" Human Development Index (HDI) and are regarded as developed countries.

The OECD's headquarters are at the Château de la Muette in Paris, France.