"It's like Hallowe'en on the Mall," commented one of the several thousand "Messiah" Sing-Along ticketholders struggling to get into the Kennedy Center last night. Bearing well-worn scores or new copies purchased for $6 in the lobby, jovial crowds of do-it-yourself Handelians streamed into the Concert Hall to join the Paul Hill Chorale for a rousing rendition of the holiday classic.

The house was packed with the would-be choristers who spilled over into the space on stage behind the Chorale and in the standing room area at the back of the hall. They obviously had a splendid time, enthusiastically applauding everyone, including themselves, the quartet of soloists, the orchestra, the Chorale, and the bevy of conductors from area churches who, along with Paul Hill and Washington Opera director Martin Feinstein, took turns in moving the massive enterprise along.

The Sing-Along marked the opening of the Kennedy Center's holiday festival of free events, which will continue for a week. Hill made a congenial host, offering a running commentary on the players and the performance, alternating scolding--"It's very ragged out there," he chided after a walk around the hall--and encouraging with claps of approval after a more or less successful chorus. His Chorale served as admirable anchor for the evening, and soprano Nelda Ormond, mezzo-soprano Jeanne Haughn, tenor Alan Kays and bass Samuel Bonds brought a welcome professional polish to the solo passages.

Each of the conductors had his own style. After Hill started things off, Leland Tetz took over with a little stand-up humor. Sondra Proctor, who also played the organ for the program, brought zest and a plea for the audience to smile while singing; Phillip McIntyre called for dramatic intensity and Feinstein whipped through the closing "Hallelujah" with a business-like firmness. The closing cheers could not have been louder if the Redskins had just won the Superbowl.