At any given Monday night, visitors to Birdland on 44^th Street might be serenaded by performers like Michael Feinstein and Chita Rivera, or by the next generation of New York’s cabaret and Broadway stars. Jim Caruso’s cast party has become an institution in its own right, offering newbies and dyed-in-the-wool pros alike a moment in the spotlight. On Thursday, the event will return to Town Hall for a “Best of Jim Caruso’s Cast Party,” with Linda Lavin, Lisa Lampanelli, Stephanie J. Block, Jane Monheit,  Julia Murney, Paulo Szot and Frank Wildhorn scheduled to perform.

Caruso says that he never intended to create the open-mic night. “I was performing in clubs at night, and during the day, doing press for a now-defunct nightclub in which absolutely nothing was happening,” he recalls. “One Monday, I used the room to throw a Christmas party for a few dozen friends from the Broadway, cabaret and jazz scenes. Everyone ate, drank and entertained each other around the baby grand until the wee hours.” The club asked him to continue the event every Monday (when most of the Broadway shows are dark), and, Caruso says, the club became the place to be. “A few weeks later, I witnessed Betty Bacall sharing a thin crust pizza with Lypsinka and Max von Essen, and I knew we were onto something special!”

At first, he says, Cast Party was like a giant cocktail party with some live music thrown in for fun. “I’d sing a few tunes, and whoever felt like showing off a bit would grab the mic. All of a sudden, I had to buy a clipboard to list who wanted to perform, and the cocktail party became much more of a show.” After the club closed its doors, the Cast Party team moved to Birdland. “Gianni Valenti, the owner, helped me develop the evening into what it is today.” And what’s that? “A three-hour impromptu variety show starring superstars, chorus kids, jazzers, composers and a few people who…um…defy description!”

The best part of Cast Party, Caruso says, is never knowing who he’ll meet there. “The anticipation is excruciating!” he says. “We’ve gotten some great press over the years, so folks from all over the planet come to check it out. The combination of tourists mingling with real-live show-folk is a joy to behold. One night, they’re watching Cheyenne star in a Broadway show; the next night, they’re rubbing elbows with him, and watching him giggle through ‘Suddenly Seymour’ with Ricki Lake!” (He swears this actually happened.) “It’s not always star-studded, but it’s an honest-to-God New York experience no matter who is in the house.”

Last year, producer Scott Siegel invited Caruso to present and host an all-star Cast Party as part of his ongoing series there. “Instead of being an open-mic, it was like a Neo-Ed Sullivan Show, with a bunch of stars and a handful of some of our most devoted and talented regulars,” Caruso says of last year’s event. “The evening was a smash…I mean who’s going to complain about a show that opens with Chita and closes with Liza?” When he asked again this year, Caruso jumped at the opportunity to do it all again.

Which is not to say that the transition from jazz club to huge theater is effortless. “Town Hall is a big ol’ theater!” Caruso quips. “After nine years, I’ve gotten pretty good at filling Birdland every week, but there’s a big difference between 200 folks and 1,500 folks! Thank goodness I have awesome friends in the business who happen to be very fancy…their names help us sell tickets!” The Town Hall show is also a benefit for The Actors Fund, which has been around since 1882 and assists people in the entertainment biz when they need help. “I’m hoping this puts me near the head of the line when I’m ready to move to the Actors Home in Englewood, NJ! It’s just a matter of time, y’all!” he adds.