The Latin American Integration Association ALADIhas admitted Cuba as a full member.
Cuba is the first Caribbean country to join the association which was set up in 1980 to encourage free trade and economic co-operation across the region.
At a meeting of ministers from member states in Uruguay, the Uraguayan foreign minister, Didier Opertti, said the news was positive for both the Cuban government and its people.
From the newsroom of the BBC World Service