Fifty years ago, a musician and scholar at the College of William and Mary, John Paul, was hired as chairman of the newly established Department of Music at the Catholic University of America.

From modest beginnings, the department grew rapidly under the leadership of Paul and his successors, Thomas Mastroiani and Elaine Walter. It was elevated in 1965 from a department within the Graduate School and College of Arts and Sciences to a school of music, and in 1984, it was named the Benjamin T. Rome School of Music in honor of a benefactor.

Today, it has alumni active in the musical life of every inhabited continent as composers, teachers, performers or administrators. Some alumni are humble singers in monastic choirs; others have gone into opera, singing or composing for top-level international audiences. Many are instrumentalists in the world's leading symphonic and operatic orchestras. It also has established special centers for advanced studies in liturgical music and the music of Latin America.

Besides regular courses, its students have been able to attend special master classes taught by such noted performers as Renata Scotto, Thomas Stewart, Andre Watts, Horacio Guttierez and Mstislav Rostropovich. It now has a roster of 340 students in 30 major fields of study, pursuing such degrees as bachelor of arts and doctor of philosophy.

The school will formally celebrate its anniversary, its growth and its mission in the world of music with a concert April 16 in the Kennedy Center Concert Hall. Music Director Piotr Gajewski will conduct the University Symphony Orchestra and Chorus and alumni soloists in Mozart's Requiem, Poulenc's "Litanies a la Vierge Noire" and the "Laudate Dominum" of Pasquale Tassone, the winner of a competition for a work commemorating the anniversary. Soloists will be soprano Fabiana Bravo, mezzo Tatiana Ishemova, tenor John Aler and baritone Valentin Vasiliu.

A less formal but exquisitely appropriate celebration was presented in the university's Hartke Theatre March 23-26: A production of Meredith Willson's musical comedy "The Music Man." This American classic is usually viewed as a homespun, sentimental bit of Americana, brightened by such great tunes as "76 Trombones," "Goodnight My Someone" (essentially the same tune with different tempo and phrasing), "Gary, Indiana," and "Till There Was You," not to mention a barbershop quartet.

But the musical is also a tribute to the power of music to transform human lives, as clearly as any opera about Orpheus or any of the Odes to St. Cecilia composed by Handel, Purcell and others.

And it has some fascinating innovations, including a parody of small-town gossip in the "Pickalittle" chorus and the use of speech rhythms in the opening salesmen's chorus and Harold Hill's monologue "Trouble."

"The Music Man" calls for an enormous cast and imaginative staging and costuming, all well provided in this production--a collaboration between the music school and the university's excellent Drama Department. The performance was on a strong professional level throughout, most notably in the work of Bryan Kennedy as Harold Hill and Sarah Dauber as Marian the Librarian.

The student orchestra was small but sonorous, expert and stylishly directed by N. Thomas Pedersen. An examination of the program reveals that there were only three trombones, but while they were playing I could have sworn there were 76.