The Pope urged healing and unity in the US Catholic Church
Pope Benedict XVI has been marking the third anniversary of him being elected head of the Roman Catholic Church by celebrating Mass in New York City.
He spoke out for the fourth time in his US visit about the suffering caused to victims of paedophile Catholic priests.
St Patrick's Cathedral in Manhattan was filled with priests, deacons and members of religious orders.
On his six-day visit to the US, his first as Pope, Benedict also promoted human rights in a speech to the UN.
On Sunday, he will visit the scene of the 9/11 attacks in New York and then celebrate Mass at Yankee Stadium before returning to Rome later on Sunday.
'A time for healing'
Pope Benedict was greeted outside St Patrick's Cathedral by the Mayor of New York, Michael Bloomberg.
A choir sang as the Pope walked down the large cathedral's central aisle. The congregation rose and applauded and some people leaned over to touch his robe or kiss his ring.
"I join you in praying that this will be a time of purification for each and every particular Church and religious community, a time for healing," the Pope said, referring to the scandal of sexual abuse of children by Catholic clergy.
"I also encourage you to co-operate with your bishops who continue to work to effectively resolve this issue."
15 Apr: Arrived at Andrews Air Force Base
16 Apr: White House luncheon; talks with Mr Bush. Meeting with US bishops and prayer service in Washington (evening)
17 Apr: Washington Mass; addressed Catholic University; interfaith meeting
18 Apr: Addresses UN
19 Apr: New York Mass at St Patrick's Cathedral
20 Apr: Ground Zero visit; Yankee Stadium Mass
More than 4,000 US Catholic clergy have been accused of sexually abusing minors since 1950.
The Church has paid out more than $2bn (£1bn) in compensation and legal fees, most of it since the scandal erupted in 2002.
The Pope said the scandal had not only caused much damage to the victims of paedophile abuse, but had diminished the reputation of the church in US society.
"A society which seems to have forgotten God and to resent even the most elementary demands of Christian morality," he said in his sermon.
The Vatican official in charge of reviewing sexual abuse claims against clergy worldwide said on Friday that the Church was considering changes to canon law governing the handling of such cases.
The official, Cardinal William Levada, did not specify the changes but said they would make it easier to remove clergy who had sexually abused children.
The sexual abuse scandal has been a recurring theme in the Pope's visit.
Addressing 40,000 people at a Washington stadium earlier in the week, he spoke of the scandal before talking privately to a group of people who had been abused by priests.
Human rights reminder
The Pope is on the second-to-last day of his six-day visit - his first to the US since being elected head of the Catholic Church three years ago.
During his speech to the UN General Assembly on Friday, the Pope said a few powerful states exercised a stranglehold on world power.
He insisted that collective action by the whole international community was the only way to solve the planet's problems.
The 81-year-old Pope said all of the UN's 192 member states had a duty to protect their people from human-rights abuses.
He also said human rights were universal, transcending cultural, political, social and religious differences.
The German-born Pope's visit to the Park East synagogue in New York made him the first leader of the Roman Catholic Church to enter a Jewish place of worship in the country.
He was welcomed by Rabbi Arthur Schneier, a survivor of the Holocaust. The Pope later attended an inter-faith meeting with leaders of other Christian denominations.