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 free-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 (which was rejected by Soviet Union and its satellite states ) by allocating American financial aid and implementing economic programs for the reconstruction of Europe after World War II, where similar efforts in the Economic Cooperation Act of 1948 of the United States of America, which stipulated the Marshall Plan that had also taken places elsewhere in the world to war-torn Republic of China and post-war Korea, but the American recovery program in Europe was the most successful one. In 1961, the OEEC was reformed into the Organisation for Economic Co-operation and Development by the Convention on the Organisation for Economic Co-operation and Development and membership was extended to non-European states. Most OECD members are high-income economies with a very high Human Development Index (HDI) and are regarded as developed countries.