Pope Francis told victims of child sexual abuse in the US that "God weeps" over what was done to them by clergy.
On the final day of his American visit, he promised to hold accountable those responsible for the scandal in the church and delivered a powerful warning to American bishops accused of covering up for paedophile priests, instead of reporting them to police.
In a gesture of reconciliation just hours before he was to return to Rome, the Pope told the victims he was "deeply sorry" for the times they came forward to report the abuse and weren't believed. He assured them that he believed them.
"I pledge to you that we will follow the path of truth, wherever it may lead," Pope Francis said in Spanish. "Clergy and bishops will be held accountable when they abuse or fail to protect children."
Then he went into a meeting with American bishops in town for a Catholic festival on the family and told them the same thing face to face.
"God weeps" over what was done to the youngsters, the Pope told them.
The gesture came as tens of thousands of the Catholic faithful streamed into the heavily fortified City of Brotherly Love for the last and potentially biggest event of the Pope's joyful six-day US visit: a Mass on Philadelphia's grandest boulevard, the Benjamin Franklin Parkway.
Organisers predicted a crowd of one million, although there were fears that the unprecedented security, including airport-style bag searches, crowd-control cattle chutes and blocked-off streets, had scared many people away and would depress the turnout.
Victim-support groups were unimpressed by the meeting in Philadelphia.
The main victims' support group, SNAP, dismissed it as an exercise in public relations.
"Is a child anywhere on Earth safer now that a Pope, for maybe the seventh or eighth time or ninth time, has briefly chatted with abuse victims? No," said SNAP's David Clohessy.