"Down with the Cuban Adjustment Act!" the boys and girls in their school uniforms chanted as they marched, skipped and hopped down the Malecon coastal highway, referring to a U.S. law that allows Cubans who reach American soil to stay. "Free Elian!"
A sea of children flowed down the 3 1/2-mile stretch where men and women have thronged in recent months calling for the return of Elian to his communist homeland.
"This was more than we had expected," said Castro, who attended the event outside the U.S. Interests Section, the American mission here.
Accompanied by their teachers and nurses dressed in white, the boys and girls waved their red or blue neckerchiefs, part of the traditional school uniform. Some smaller children giggled and waved at television cameras broadcasting the event live across the island.
About 1,000 students in the 4th to 6th grades circled the mission, following Castro's orders, to prevent younger children from throwing anything at the building.
Castro and other senior officials, including Ricardo Alarcon, president of Cuba's National Assembly, sat in the first row facing a permanent stage erected recently outside the mission. They listened to a series of brief and virulent speeches by small children blasting American "imperialism."
"Long live Fidel!" the children cried repeatedly. "Socialism or death!"
"I studied with Elian," said Yailen Fuentes, 7, a girl from Elian's hometown of Cardenas, 90 miles east of Havana. "We came here for him -- everyone for him."
Elian was rescued off Florida in November after his mother and 10 others perished in a sea journey to the United States.
He was reunited with his father, Juan Miguel, on April 22 after the boy was seized during an armed federal raid at the home of the Miami relatives. Father and son are staying in Washington, along with other relatives from Cuba and several of Elian's Cuban classmates, pending an appeal by the boy's Miami relatives to keep him in the United States.
A week ago, a federal appellate court in Atlanta sided with Elian's father, who says only he has the right to speak for his son. The boy's Miami relatives had been seeking a political asylum hearing for the child.
The father has said he wants to return with his son to Cuba. But under a timetable outlined by Attorney General Janet Reno, Elian cannot leave the United States until June 21, to give his Miami relatives a chance to appeal the latest ruling.