In this article, Maria Claudia Drummond discusses the recent phenomenon of representative institutions which become part of the machinery of free trade areas, or economic unions between groups of sovereign states in the continent of South America. After the failure in the 1960s of ambitious schemes to establish a Latin American Free Trade Area a more modest project emerged, starting with the Declaration of Iguaçu of 1985 signed by Argentina and Brazil. This became the starting point for establishing a common market in the southern cone of South America, and was enlarged to include Paraguay and Uruguay to constitute the Mercosul union of the four nations, formalized in the Treaty of Asuncion in 1991. The article describes the institutions of Mercosul, a Council, an Executive, a Trade Commission and a Joint Parliamentary Committee, which could be developed later into a full Mercosul Parliament. These are completed by a Consultative Forum for the independent representation of corporate economic and social interest groups