Most of the schools have issued apologies and some have negotiated settlements with the accusers.

In the case of St. George’s, a coed boarding and day school for grades 9 to 12, officials said in the report that after a nearly yearlong investigation, they had received 26 “credible first-hand accounts (as well as other corroborating evidence) strongly suggesting that three former employees of the school engaged in sexual misconduct with regard to multiple students.” In addition to those three, the report said that three other former employees had one victim each and that some students had engaged in sexual misconduct, including, in one case, the rape of a freshman.

The school so far has named one perpetrator, Al Gibbs, the former athletic trainer, who was fired in 1980 and died in 1996. It did not name the other employees, whom the school also failed to report to the authorities at the time. Having learned of their actions during the current investigation, the school has referred them to the Rhode Island State Police, which is carrying out its own investigation.

The report said the school would pay for therapy for victims, which could begin immediately. The school has established a victims’ support fund to provide reimbursement for past treatment. It has also set up telephone numbers for victims and said it was forming a victims’ support advisory group. It also plans to conduct education and training programs for all employees and students. In addition, the board of the school is considering whether to rename a dormitory that had been named in honor of Tony Zane, who had been the head of school during the time of the abuse.

Anne Scott, a 1980 graduate who has said that Mr. Gibbs molested and raped her, said Thursday that she was disappointed in the school’s investigation because it was not independent. She noted that the chief investigator, Will Hannum, was a partner in a firm in which another partner represents and advises the school.

“If he had been truly independent, he would have looked deeper and harder at the roles that the leadership has played in this,” Ms. Scott said. “He would have looked more actively at the scope of the perpetrators, which goes beyond three. And he would have drawn lessons learned. There’s nothing about the enormity of that and the depth of change that will be required.”