The 50th year of Monsignor Edward J. Duncan's service as chaplain to Roman Catholic students and as director of the Newman Foundation at the UI will be celebrated Saturday through Monday. A commemorative Mass will be celebrated by Cardinal Pio Laghi, the former papal nuncio, at 10:30 a.m. Sunday. An anniversary luncheon will follow at the UI Assembly Hall. A concert will be presented at 6 p.m. in St. John's Chapel by the chapel choir and the UI Chorale, with string, brass and wind ensembles. A full-day symposium, "Building the Church of Tomorrow: Educating the Youth of Today," will be presented Monday in the Krannert Center for the Performing Arts. Participants will include Laghi; Father Theodore Hesburgh, president emeritus of Notre Dame University; theologian Martin Marty; and Denise Carmody, director of the Warren Center for Catholic Studies. Duncan became chaplain at St. John's and director of the Newman Foundation in October 1943, only a few years after his ordination into the priesthood. He is credited with stabilizing the student center's shaky finances during his early years at St. John's and with strengthening and greatly expanding its programs and accredited college courses. A sports enthusiast, he has long served as chaplain to the university's athletes, for which he has been honored with an honorary "I."