Cardinal George says most of the incidents happened decades ago, by priests he's never met or talked to, but he wrote the letter to be, as it says, accountable and transparent.
"It's always important to tell the truth since the publications of dossier's of events that happened in the 80's before I got here is going to be nonetheless the occasion for a lot of conversation I thought I better put it in some perspective, so that was the purpose of the letter," he said.
As part of a court settlement, the church will soon disclose documents identifying 30 former clergy members accused in sexual abuse cases and the files will also identify church officials that are accused of protecting them.
The cardinals letter goes on to mention father Daniel McCormack and the handling of his case, one that happened on Cardinal George's watch.
"Sometimes people think we all knew everything about him before and we were reckless with children's concerns and care that isn't true, he deceived a lot of people," he said.
Members of the Survivors' Network of Those Abused by Priests (SNAP) handed out leaflets outside Holy Name Cathedral, asking parishioners to ignore Sunday's letter from the cardinal, calling it self-serving.
"Please get the information directly from the source and not from someone who is trying to protect themselves and the institution for which they work," said Kate Bochte, SNAP.
Parishioners that heard the cardinal Sunday hope the Catholic Church has learned from the past incidents and can grow from it.
"They're learning to deal with these issues in a major way and I'm really impressed by the new pope and the actions he's taking," said parishioner Mary Adami. "I think things are starting to turn around for the church."
The documents will be turned over on Wednesday then will be made public a week later.