(BBC) Pope Benedict XVI is celebrating an open-air Mass in the central Mexican city of Silao on his first visit to the Latin American country.
Hundreds of thousands of people are attending the service, under a large statue of Christ in the city's Bicentennial Park.
On Saturday, the Pope met President Felipe Calderon, with whom he discussed Mexico's drugs violence.
Mexico is the world's second most populous Catholic country.
This is the showpiece event of Pope Benedict's first trip to Mexico - a huge open-air Mass to some 300,000 followers in the Bicentennial Park in Silao.
The excitement amongst the gathered Catholics is palpable with the youth playing a very visible part in the proceedings. People are dressed in white and yellow and many are looking for shade to protect themselves from the fierce early morning sun.
But the atmosphere is one of celebration. That the head of the Catholic Church will lead Sunday Mass in this small town is more than many here had expected to see. The Church hierarchy hopes the event will help reaffirm the faith in Mexico where it has been losing ground to evangelical churches in recent years.
"We could hardly sleep because of the emotion and now we can see the Pope," said Xochitl Alvarez, an indigenous woman who said she had travelled hundreds of miles from southern Mexico.
The main candidates for July's presidential election were expected to attend, as well as Mexican tycoons including Carlos Slim, the richest man in the world, reports say.
Addressing a group of children and young people on Saturday, the Pope told them they were "not alone" in their faith.
He urged Mexico's adults to "protect and to care for children, so that nothing may extinguish their smile". He said he would pray that Mexico would be "a home where all [God's] children can live with serenity and harmony".
The Pope also spoke about the drugs violence which has killed more than 47,000 people in Mexico over the past five years.
He cautioned against acts of revenge, saying: "The disciple of Jesus does not respond to evil with evil."
Drug gangs' truce call
Pope Benedict XVI wears a traditional Mexican hat while driving through the crowd in Silao The Pope's visit to Silao is the showpiece event of his first trip to Mexico
The Mexican presidency said the Pope's private meeting with Mr Calderon had covered a range of topics including climate change and organised crime.
The authorities in Guanajuato state have implemented tight security for the pontiff's visit, and the archbishop of Leon, Jose Guadalupe Martin Rabago, called on drugs gangs to observe a truce for the duration of his stay.
The BBC's Will Grant in Guanajuato says few expect that the Pope's visit will have a significant impact on Mexico's complicated political and military situation, but the country's Catholics are largely glad of his presence.
They say he is a potent symbol of peace and reconciliation at a time when Mexico badly needs it, says our correspondent.
However, his tour has been dogged by protests over child sex abuse scandals in the Catholic Church and criticism of his stance of gay rights.
Some 88% of Mexicans - almost 100 million people - are Roman Catholic, and the Pope's predecessor, John Paul II, was a regular visitor to the country.
On Monday, the Pope's tour will take him to Cuba.
He has said the island's Marxist structure "no longer corresponds to reality" and called for "new models" of government to be put in place.