Another alleged victim of abuse says his life has been ruined.
An academic who compiled a report for the Church on how to deal with abuse says not enough was done.
The Catholic Church in Scotland insists its child protection procedures have improved dramatically since the 1990s and allegations of abuse now are rare.
The Roman Catholic Church is no stranger to scandal, but until now Scotland has not been engulfed by allegations of abuse.
That may be changing.
The BBC has also spoken to another alleged victim who is not among the 20 new allegations.
Chris claims he was abused by a priest in the 90s, from the age of nine or 10 until he was into his early teens.
"He would get me to perform sexual acts on him and he would perform sexual acts on me," he said.
"I was very concerned about their unwillingness to actually expose individual priests who were leading double lives," Alan Draper Author of a report for the Catholic Church in Scotland said.
"Away from the family home, in the family home, in the church, in their vehicle.
"There's many people out there who have been abused."
Chris' story didn't come to light until last year. Police took him seriously, but the case never came to court.
The Church says it removed the priest involved from his parish as soon as the allegations were made and the police were informed.
It insisted the case had been "handled in complete accordance with the guidelines".
A spokesman added, "The Church sent its file to the Vatican in July last year and now awaits a decision."
But how common were such claims?
In the mid-1990s, an academic was appointed to advise the Church on sexual abuse and how to respond to it.
Alan Draper asked Scotland's eight bishops how much they knew.
The BBC has seen the letters which they sent in reply to Mr. Draper, which refer to 20 allegations of child abuse by priests.
Mr. Draper says he wanted independent experts to investigate further, but the bishops disagreed.
He said, "I was very concerned about their unwillingness to actually expose individual priests who were leading double lives.
"They were very reluctant to do that, and I felt that was totally inappropriate. It's not what your sexuality is, it's how you're managing your sexuality.
"Certainly there's strong evidence to say some of the priests were out of control sexually, whether they be homosexual or heterosexual. The file should be made open to an independent group, preferably chaired by a judge."
The Church said Mr. Draper was involved "at an early stage in the development of policies and procedures but was replaced when others with greater competence were engaged".
The letters seen by the BBC suggest some priests were reported to police and removed from parishes, while others were not.
Now more alleged victims are coming forward after Cardinal Keith O'Brien admitted sexual misconduct after resigning as Archbishop of St Andrews and Edinburgh following allegations by other priests.
He does not face any criminal allegations, or any claims of child abuse.
Lawyer Cameron Fyfe said, "I'm acting for six clients who allege abuse, two of whom have come forward just in the last few weeks since the Keith O'Brien scandal.
"Some of them go back to the early 1980s, but two of them have been within the last 10 years."
He said two of his clients claimed to have been raped while they were children, with the attacks taking place in the late-1980s and mid-1990s.
Mr. Fyfe said that under Scots law, cases should be brought within three years.
But he said that was "totally unrealistic because victims of sexual abuse often lock away the memories of the abuse and can't come to terms with it".
In a statement, the Catholic Church in Scotland said it had applied nationally agreed guidelines on abuse since 1999.
It said, "All allegations are notified to the police. The Church recognizes that the statutory authorities are the responsible bodies for investigation.
"All necessary steps are taken to remove anyone in danger from situations of risk."
It added that a "national coordinator" for child protection was a key part of its "safeguarding structures."
