Raul Castro (top right) hailed membership of the Rio Group
Latin American leaders have urged US President-elect Barack Obama to end the 46-year trade embargo on Cuba.
Their call came at a summit in Brazil where they formally accepted Cuba into the Rio Group of 23 Latin American and Caribbean nations.
"Cuba returns to where it always belonged," said Venezuelan President Hugo Chavez, a fierce critic of the US.
Correspondents say the move is a blow to long-standing US efforts to exclude Cuba from regional organisations.
Cuba was expelled from the Organisation of American States in 1962 at the height of the Cold War.
Brazilian President Luiz Inacio Lula da Silva told the summit in the north-eastern resort of Costa do Sauipe that he hoped the new Obama administration would bring " a change in US policy towards Latin America and the Caribbean".
That included, President Lula said, an end to the embargo on Cuba "which no longer makes sense - neither economic nor political. In fact, there is no reason for it."
Cuban President Raul Castro, on his first foreign tour since taking over from his brother Fidel earlier this year, has said he is open to meeting Mr Obama to discuss the issue of the embargo.
He described his country's entry into the Rio Group as a "transcendental moment in our history".