What do you call the mass before the graduation?

Answer 1

Baccalaureate Service or Mass

A baccalaureate service is a celebration which honors a graduating senior class from a college or high school. The event is often, but not necessarily, of a religious nature, although it is almost invariably Christian. At many Yeshivas and other universities with religious affiliations, the baccelaureate service (or, baccalaureate mass in the case of institutions affiliated with the Catholic Church and its orders) will be celebrated as a religious ceremony. In some parts of the US this service is called Vespers. (Wikipedia) For the source and more detailed information concerning your request, click on the related links section (Wikipedia) indicated at the bottom of this answer box.