Analysis by Sarah Grainger BBC News, Caracas:
The US and Canada were deliberately excluded from this summit, but Cuban President Raul Castro has been welcomed with open arms.
The heads of state of 32 countries in the region have come to Caracas for the inauguration of the new organisation. Only President Humala has stayed away, amid continuing protests over mining in Peru.
While US exclusion from the meeting is clearly a snub to Washington, the Venezuelan government says the new organisation will foster regional ties and look at ways of insulating the region from economic problems in the US and Europe.