The supreme organ of the party is its congress, which is summoned by the outgoing central committee and held every four years. The congress is composed of delegates elected by the respective lower organs proportional to each organ's membership size. The congress approves its theses after a wide discussion period inside the organizations and may also change the party's program and statutes. All the decisions of the congress are made by the delegates voting. With the exception of the voting for the central committee, which a recent Portuguese law requires to be secret, all voting, including the approval of the theses, are conducted by a show of hands. The theses, after approval, guide all the party's political actions and stances until the next congress.