COSAC was created in May 1989, at a meeting of the Presidents of the National Parliaments of the EU Member-states in Madrid, with the objective of strengthening the role of these Parliaments regarding the process of European construction.

Thus, COSAC institutionalised a form of cooperation between the committees of European Affairs of the different national Parliaments and the representatives of the European Parliament.

The first COSAC meeting was held in Paris, in November 1989 and COSAC was consecrated in the Protocol annexed to the Treaty of Amsterdam on the Role of the National Parliaments, signed by the Heads of State and Government in June 1997, and entered into force on 1 May 1999.

Under this Protocol, COSAC has the capacity to send all and any contributions considered relevant to European institutions.

COSAC meets twice a year in which each national Parliament is represented by six members. The parliaments of the countries which are candidates to join the European Union or are involved in accession negotiations are also invited to participate with three observers each.

Normally, the COSAC meeting takes place in the capital of the country holding the presidency of the European Union, as will occur with the XXXVIII COSAC in Lisbon, in 2007.