Choruses tend to age at about the same rate as dogs, and in chorus-years, the Choral Arts Society of Washington is well beyond its dotage. That it has prospered into its 25th year with ever-increasing vigor and ever-maturing artistry is testimony to the vision and imagination of founder and director Norman Scribner, who has challenged his singers with daring scores, wooed them with romantic ones and delighted them with traditional seasonal programs. Under his stewardship wonderful conductors have led them and wonderful orchestras have collaborated with them, and Washington's choral activity owes much of its flourishing health to the generosity of his cooperation with this city's other fine choral leaders.

Scribner and his group celebrated their first quarter-century of musicmaking with a gala concert in the Kennedy Center's Concert Hall Sunday night that featured the spirit that has been their hallmark and some of the people who have been so important to them through the years. Paul Hume, music critic emeritus of The Washington Post and a longtime Choral Arts Society supporter who never forgets the details of a performance or of a conversation, hosted the festivities with his inimitable reminiscences. Mstislav Rostropovich, who has led the chorus in so many splendid performances, resurrected two movements of the Rachmaninoff "Vespers" that was such a triumph a couple of years ago and then brought out his cello for a glorious performance of the Sarabande from the Third Suite for Unaccompanied Cello by Bach, and for the Schumann "Traumerei," a piece that usually sounds cloyingly sweet but that, on this occasion, sang movingly. Pianist Eugene Istomin offered a fine reading of a movement from the Mozart Piano Concert No. 21 and some dazzling Schubert.

But it was the chorus that held the spotlight. From the smashing Handelian cry of "Let Their Celestial Concerts All Unite" that opened the concert to the closing performance of the "Hallelujah" Chorus with hundreds of past Choral Society members joining in, there was one splendid moment after another: a performance of the sixth movement of the Brahms Requiem that was full of passion and affirmation; Dirksen's excellent "Welcome, All Wonders!," which has become a theme song of Choral Arts Society Christmas concerts; the Gloria from the Bach B Minor Mass, sung with remarkable clarity; and five movements of Orff's "Carmina Burana," almost brutal in its visceral energy.

This may have been a celebration of the past 25 years, but in energy and spirit it sounded a lot like a kickoff for the next 25.