Speaking on the final day of his first US trip Pope Francis used an address in Philadelphia to tell gathered bishops that 'God weeps' for the victims of clerical sexual abuse and those responsible will be 'punished'.
The Pope's comments came after he met with abuse victims and the day after he led a packed Mass at Madison Square Garden in New York.
The Pope was greeted by United Nations secretary-general Ban Ki-moon as he arrived to address the General Assembly.
Thousands of people lined the streets of New York to welcome the pontiff, who also attended a service at St Patrick's Cathedral.
At the General Assembly, Pope Francis is expected to discuss the need for peace, the refugee crisis and how poverty and bad governments contribute to war and migration.
Pope Francis' first US visit has sparked an unexpected craze among Americans - dressing dogs up in miniature versions of his papal garb.
A five-year-old girl managed to breach the Pope's security to deliver him an important letter.
Pope Francis is due to arrive in the US, but he will face a political test on Thursday when he addresses Congress.