This chapter focuses on Latin American state participation in international organizations at the regional and subregional levels. It discusses Latin America-wide organizations designed to promote both political and economic cooperation among the member states and to increase the region’s bargaining power with the rest of the world. After the Second Lima Congress in 1865, the Latin American states abandoned initiatives directed toward union and began to place their reliance on international law. Post-World War II economic integration efforts continued to illustrate an inter-Latin American “love-hate” relationship. Latin American integration efforts after World War II differed fundamentally from the earlier nineteenth-century attempts. The Inter-American System also gave impetus to and supported economic integration in Latin America. Economic integration had wide appeal in Latin America, both as an “independence movement” against external (especially US) economic domination and as a means to Latin American development.