The cooperation procedure was introduced by the Single European Act in 1987 in order to increase the weight of the European Parliament.

After the first reading of the Commission proposal in the European Parliament, the Parliament issues an opinion. Thereupon the Council adopts a so-called "common position". In the second reading, the Parliament may amend or reject the common position. In contrast to the codecision procedure, the final decision ultimately lies with the Council alone; however, unanimity is required for the adoption of bills that have been amended or rejected by the Parliament. The cooperation procedure now only remains in use for certain parts of economic and monetary policy.