Leaders were greeted by Brazilian Foreign Minister Celso Amorim, who called the meeting "the beginning of a historical movement."
"It's a cultural and spiritual promotion, but we also would like to see practical results from the beginning of this historical movement," said Amorim during his Monday opening remarks at the summit.
Both Arab and Latin leaders are expected to discuss such issues as trade, poverty reduction, and other shared goals during their two days of talks beginning Tuesday.
In all, 22 Arab leaders are to attend the summit, including new Iraqi President Jalal Talabani. At least 10 leaders from South America will also participate.
U.S. and Israeli officials expressed concern the meetings could serve as a platform to launch attacks on both nations' policies in the Middle East.
The Israeli embassy in Brazil last week released a statement saying, "The positions and worries of Israel regarding the summit have been expressed directly to the government of Brazil and other South American governments."