About two million people are on Copacabana Beach in Rio de Janeiro for the last evening of World Youth Day with Pope Francis.
The BBC reports their vigil on Saturday night marks the climax of the five-day festival, which culminates in a huge Mass on Sunday.
The Pope on Saturday called on young people to be the actors of change in society and rebuild the Roman Catholic church.
Speaking on a huge stage, Pope Francis referred to street protests which have been taking place in Brazil for more than a month.
"The young people in the street are the ones who want to be actors of change. Please don't let others be actors of change," he told the crowd at the vigil.
"Keep overcoming apathy and offering a Christian response to the social and political concerns taking place in different parts of the world."
He also urged young people to shun fleeting fads and be "athletes of Christ."
Clergy urged to leave the comfort of their churches
Earlier, Pope Francis challenged Catholic clergy to leave the comfort of their churches and reach out to the poor and the marginalised.
In a speech to 1000 bishops and clerics in the Cathedral of St. Sebastian in Rio de Janeiro on Saturday, he said they should go to the favelas, as Brazilian shanty towns are known.
"We cannot keep ourselves shut up in parishes, in our communities, when so many people are waiting for the Gospel," he said.
On Friday, Pope Francis also spoke about the lack of faith in political institutions perceived as selfish and corrupt by young people.
"Jesus is united with so many young people who have lost faith in political institutions, because they see in them only selfishness and corruption,'' Pope Francis said.
The BBC reports the Pope also expressed understanding for Christians who had lost faith in the Church because of what he called the "incoherence of Christians and ministers of the gospel".