A congress is a formal meeting of representatives from different countries (or by extension constituent states), or independent organizations (such as different trade unions).

The term Congress was chosen for the United States Congress to emphasize the status of each state represented there as a self-governing unit. Subsequently to the use of congress by the US legislature, the term has been adopted by many states within unions, and by unitary nation-states in the Americas, to refer to their legislatures.

Congresses of nations

The following congresses were formal meetings of representatives of different nations:

• The Congress of Berlin (1878), reorganizing conditions in the Balkans,
• The Congress of Gniezno (1000)
• The Congress of Panama was an 1826 meeting of representatives from several Latin American republics organized by Simon Bolivar in an attempt to promote Pan-American unity.
• The Congress of Tucumán (1816)
• The Congress of Vienna (1815), reorganizing Europe after the Napoleon wars,
• The National Congress of Belgium was a temporarily legislative assembly in 1830, decided to create a constitution for the new state.

• The Congress of the Council of Europe.

Congress within Nations

• The United States Continental Congress

Countries with Congresses and presidential systems:

• The Congress of Guatemala (Spanish: Congreso de la República) is the unicameral legislature of Guatemala.
• The Congress of Honduras (Spanish: Congreso nacional) is the legislative branch of the government of Honduras.
• The Congress of Mexico ( ) is the legislative branch of Mexican government.
• The Congress of Paraguay is the bicameral legislature of Paraguay.
• The Congress of the Argentine Nation (Spanish: Congreso de la Nación Argentina) is the legislative branch of the government of Argentina.
• The Congress of the Dominican Republic is the bicameral legislature of the Dominican Republic.
• The Palau National Congress (Palauan: Olbiil era Kelulau) is the bicameral legislative branch of the Republic of Palau.
• The Congress of the Federated States of Micronesia is the unicameral legislature of the Federated States of Micronesia.
• The Congress of the Philippines (Filipino: Kongreso ng Pilipinas) is the legislative branch of the Philippine government.
• The Congress of the Republic of Peru (Spanish: Congreso de la República) is the unicameral legislature of Peru.
• The Congress of the United States is the bicameral legislative branch of the United States federal government.
• The National Congress of Bolivia is the national legislature of Bolivia.
• The National Congress of Brazil ( ) is Brazil's legislature.
• The National Congress of Chile (Spanish: Congreso Nacional) is the legislative branch of the government of Chile.
• The National Congress of Ecuador is the unicameral legislature of Ecuador.