Pope Francis will greet scores of young pilgrims Thursday at the welcoming ceremony for World Youth Day in Rio de Janeiro.
In the highlight event of the pontiff's week-long trip to Brazil, as many as one-million people are expected to be on hand as Francis addresses young Catholics from around the world on Rio's famed Copacabana beach.
Before the ceremony, the pope will visit one of Rio's notorious slums, or favelas, continuing his mission to call attention to the poor and marginalized.
During a visit Wednesday to the shrine dedicated to Our Lady of Aparecida, the country's symbol of the Virgin Mary, Francis urged 200,000 faithful to shun materialism and focus on "the outcasts of society."
The pontiff also warned Latin America against legalizing drugs when he visited a treatment center for drug addicts and alcoholics.
He said the eradication of "the scourge" of drug trafficking requires an act of courage from society as a whole, and said a reduction in drug use will not be achieved by liberalizing laws.
The pontiff, 76, received a thunderous welcome Monday on arrival in Rio, cheered by thousands of people who lined the streets to view his passing motorcade. But the trip was marred by a major security lapse after his car took a wrong turn onto a busy street and was mobbed by well-wishers.
Analysts acknowledged serious security challenges, but they said the wishes of the pope to be out among the public made it difficult to ensure full protection.