John Farrell, 73, and Paul Kelly, 64, were convicted of several charges against six former pupils of St Ninian’s School in Falkland, Fife, after a long-running trial at the High Court in Glasgow.
The men were remanded in custody after a jury found Farrell, from Motherwell, North Lanarkshire, guilty of three counts of indecent assault and a charge of assaulting a boy with a belt.
Kelly, from Plymouth, Devon, was convicted of four counts of indecent assault and three assault charges, including hitting a boy’s head off sinks at the school, which was run by members of the Catholic religious order the Congregation of Christian Brothers.
St Ninian’s housed about 45 vulnerable boys in need of care until its closure in 1983.
Farrell and Kelly committed the crimes over a four-year period from 1979 against pupils aged 11 to 15.
Kelly was found guilty of having oral and anal sex with boys and on other occasions made pupils perform sexual acts on themselves, on each other, and on him.
The pair were tried on about 50 charges but the jury, returning a verdict on their eighth day of deliberations, found them not guilty, or the offence not proven, for all but 11.
Charges against three other men were earlier dropped.
The trial before Lord Matthews began in April and followed one of the biggest abuse inquiries of its kind ever carried out by Police Scotland.
Several victims attended court and cried “yes” when the judge told the men, previously on bail, that they would be remanded in custody ahead of sentencing next month.