High Quality Content by WIKIPEDIA articles! The Organisation for Economic Co-operation and Development (OECD) (in French: Organisation de coopération et de développement économiques, OCDE) is an international organisation of 30 countries that accept the principles of representative democracy and free-market economy. Most OECD members are high-income economies with a high Human Development Index (HDI) and are regarded as developed countries. It 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.