Boston College spokesman Jack Dunn said Monday that the school respects O'Malley and regrets that he didn't attend graduation.
Dunn said school officials extended the invitation to Kenny before the bill's introduction and that the college "fully supports the church's commitment to the unborn."
But C.J. Doyle, executive director of the Catholic Action League and one of the protesters, said that too many Catholic institutions have compromised their identity.
"What rational person can reasonably be expected to take seriously Catholic opposition to abortion when our own Catholic institutions honour someone who's trying to legalise abortion in his country?" he said.
Also at the ceremony were two graduate business students who were injured in the Boston Marathon bombings were to receive their diplomas. Brittany Loring and Liza Cherney are graduating from the Carroll School of Management.
Loring needed three operations after her left leg was struck by shrapnel from the first of the twin blasts on April 15. Cherney was standing next to her close friend and classmate and was also badly hurt.
- AP