The police investigation concerns monks who taught at the Fort Augustus Abbey school in the Highlands in the 1960s and 70s. It has since closed.
Police said they had been investigating since March following a report from a former pupil and further allegations from a BBC documentary.
Charity Children 1st has set up a dedicated support line for anyone affected.
An 80-year-old man was charged in September and three men have now been reported to the procurator fiscal, police said.
A force spokesman said: "In relation to the investigation into historical physical and sexual abuse at Fort Augustus Abbey, Police Scotland have interviewed and spoken with a number of victims and witnesses of abuse and as a result have reported three men to the Crown Office and Procurator Fiscal Service.
The inquiry was launched after a man in his 40s alleged he suffered both physical and sexual assaults while a pupil at the abbey.
The spokesman said: "This is very much an ongoing investigation, which was initiated by Highland and Islands division in March 2013 and has extended to liaison with a number of law enforcement agencies both across and outwith the UK.
"We understand that it is very difficult for victims of abuse to speak about their experiences and a help line run by Children 1st is available to provide support and advice to those who may be affected by the investigation."
Children 1st traditionally helps children, young people and families recover from abuse, neglect and violence, and campaigns for children's rights.
It emerged in September that alleged victims were planning to launch a legal action against the Catholic Church. Six former pupils had reportedly contacted an English law firm to sue the Benedictine Order.
The help line number is 0800 345 7457.