Pope Benedict XVI told America's Roman Catholic leaders that the clergy sex abuse scandal has sometimes been "very badly handled" by the church.
Benedict's remarks came at a prayer service on Wednesday with hundreds of US bishops at a national shrine in Washington.
The comments mark the second time the pope has addressed sex abuse on his journey to the United States, and they are the harshest criticism yet of the bishops themselves.
On his flight to America, the pope said he was deeply ashamed of the scandal and would fight to keep pedophiles out of the priesthood.
Benedict addressed clerical molesters in the wider context of secularism and the over-sexualisation of America. "What does it mean to speak of child protection when pornography and violence can be viewed in so many homes through media widely available today?" he asked.
The pope spoke after a talk by Cardinal Francis George of Chicago, Illinois, president of the US Conference of Catholic Bishops.
George said the consequences of the clergy abuse scandal "and of its being sometimes very badly handled by bishops makes both the personal faith of some Catholics and the public life of the church herself more problematic."
Benedict seemed to agree with that assessment.
"Responding to this situation has not been easy and, as the president of your episcopal conference has indicated, it was sometimes very badly handled," he said.
Benedict said it was important to remember that the vast majority of priests served faithfully, but it also was the bishops' "God-given responsibility" to reach out to those who had been "so seriously wronged.