The Central American Integration System (Spanish: Sistema de la Integración Centroamericana, or SICA) has been the economic and political organization of Central American states since 1 February 1993. On 13 December 1991, the ODECA countries (Spanish: Organización de Estados Centroamericanos) signed the Protocol of Tegucigalpa, extending earlier cooperation for regional peace, political freedom, democracy and economic development. SICA's General Secretariat is in El Salvador.

In 1991, SICA's institutional framework included Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama. Belize joined in 1998 as a full member, while the Dominican Republic became an associated state in 2004 and a full member in 2013. Mexico, Chile and Brazil became part of the organization as regional observers, and the Republic of China, Spain, Germany, Georgia and Japan became extra-regional observers. SICA has a standing invitation to participate as observers in sessions of the United Nations General Assembly, and maintains offices at UN Headquarters.

Four countries (Guatemala, El Salvador, Honduras, and Nicaragua) experiencing political, cultural and migratory integration have formed a group, the Central America Four or CA-4, which has introduced common internal borders and the same type of passport. Belize, Costa Rica, Panama and the Dominican Republic subsequently joined the CA-4 for economic integration.

Between 14 November and 20 December 1907, after a proposal by Mexico and the United States, five Central American nations (Costa Rica, El Salvador, Guatemala, Honduras and Nicaragua) took part in the Central American Peace Conference in Washington, D.C. sponsored by United States Secretary of State Elihu Root. The five nations, all former Spanish colonies, had previously tried to form a political alliance. Their first attempt was the Federal Republic of Central America, and the most recent effort was the founding of the Republic of Central America 11 years earlier.

The participants concluded the conference with an agreement creating the Central American Court of Justice (Corte de Justicia Centroamericana). The court would remain in effect for ten years from the final ratification, and communication would be through the government of Costa Rica. It was composed of five judges, one from each member state. The court heard ten cases, five of which were brought by private individuals (and declared inadmissible) and three begun by the court. The court operated until April 1918 from its headquarters in Costa Rica; despite efforts beginning in March 1917 (when Nicaragua submitted a notice of termination of the agreement), it then dissolved.

Reasons for the agreement's failure include:

At the end of World War II, interest in integrating the Central American governments began. On 14 October 1951 (33 years after the CACJ was dissolved) the governments of Costa Rica, El Salvador, Guatemala, Honduras and Nicaragua signed a treaty creating the Organization of Central American States (Organización de Estados Centroamericanos, or ODECA) to promote regional cooperation and unity. The following year (12 December 1952), ODECA's charter was amended to create a new Central American Court of Justice (Corte Centroamericana de Justicia, or CCJ) without the time limit of its previous incarnation.

The Charter of San Salvador was ratified by all Central American governments, and on 18 August 1955 their foreign ministers attended its first meeting in Antigua Guatemala. The Declaration of Antigua Guatemala authorized subordinate organizations of ODECA to facilitate economic cooperation, better sanitation and progress in the "integral union" of the Central American nations.