"This is the biggest event of the Summer School session, and it is the only one which springs from the Summer School itself," Dee Hiatt, conductor of the Harvard Summer School Chorus, said yesterday in reference to the Chorus's annual summer concert, which will take place tonight at 8 p.m. in Sanders Theatre. The program for the concert contains a variety of musical styles, ranging from 17th century English Renaissance music to major contemporary works for mixed chorus and a brass ensemble.

The concert will open with two selections by Ralph Vaughan Williams, "O Taste and See" and "O Clap Your Hands." The first piece was composed for the coronation of Queen Elizabeth II. Then the chorus will sing the Apparebit Repentina Dies" by Paul Hindemith. It was composed in 1947 for a Symposium on Musical Criticism held at Harvard and was performed then by the Harvard Glee Club and Radcliffe Choral Society with the composer conducting.

After an intermission, the Summer School Chamber Singers, with their own instrumentalists, will present four madrigals from the Elizabethan Age. These madrigals show the Italian influence which prevailed in English court life at that time.

Then two settings of the "Ave Verum Corpus" will be performed, one by Josquin des Prez for three voices and one by William Byrd for four voices. The "Ave Verum Corpus" text is a Communion hymn which has been set by composers of all ages.

The concert will close with Psalm 84, "Wie lieblich sind deine Wohnungen," by Heinrich Schutz.

This year's Harvard Summer School Chorus, with a membership of nearly 200, is the largest ever assembled. All people at the Summer School who want to sing in it are welcome as members and there are no competitive try-outs. The chorus has been rehearsing for this concert every Tuesday and Thursday evening since the beginning of the Summer School

Miss Hiatt, conductor of the chorus, is associate professor of Music at Smith College. As Director of Choral Music at Smith she has conducted the Glee Club and the Choir in concerts given in many eastern cities. She founded the Smith College Chamber Singers, who have made six European tours. According to the Christian Science Monitor, "Miss Hiatt is a master of her craft and art...Under her supple hands the chorus sounded well-nigh flawless---secure, sonorous, and full of spirit."