At the Pennsylvania Playhouse, the laughter was so loud you could hear it across the street. I don't know what was playing over there.

Fortunately, there are better gags than that one in Neil Simon's ''Laughter on the 23rd Floor,'' now at the Bethlehem theater. They flow freely in this story about the writing staff of Sid Caesar's ''Your Show of Shows'' television classic.

The liberal use of the ''f---'' and ''s---'' words are surprising for a Simon play (it opened on Broadway in 1993, decades later than his more familiar works). But other Simon trademarks are here. He mixes shtick with seriousness and schmaltz. And he uses a fictional portrayal of himself, occasionally addressing the audience to explain characters or set a scene.

As the play opens, Lucas Brickman (Jeff Chirico, based on the real life Simon) has just begun to work for Max Prince (Pat Kelly). The writers drift in one by one: Milt Field (Chip Rohrbach), who distinguishes himself by his outlandish wardrobe; Val Skolsky (Gary Boyer), the Russian emigre and head writer; Brian Doyle (Larry Harris), who brags about selling yet unwritten screenplays; the straight-laced by comparison Kenny Franks (Chip Williams); secretary and wanna-be comedy writer Helen (Rebecca Wenhold), and Carol Wyman (Rebecca Pieper), who reluctantly adjusts to the male-oriented atmosphere.

The gags flow throughout. An example: ''He's accused of being a card-carrying communist.'' ''He had cards printed?''

Serious elements are also introduced, as the McCarthy witch-hunt has begun, and NBC is interfering with Prince's show.

After Prince shows up, he turns out to be more insane than his writers, punching holes in the wall and ranting about, well, everything. Actually one writer might be crazier: the always late, hypochondriac Ira Stone (Peter Sanchez).

The cast does a great job with these sometimes hard roles. Kelly does not quite have the bombast you would expect of the real-life Caesar, but he deftly captures both his hyperactive tension and his love for his writers. Sanchez does a wonderful Woody Allen, who wrote for Caesar. Simon based Sanchez's character on Mel Brooks, but that should not matter unless you have strong feelings about the Allen vs. Brooks film controversy.

Director Ralph Montesano has created a show that puts the audience in the palm of his hand. They must get heavy after awhile.

''Laughter on the 23rd Floor,'' 8 p.m. Friday and Saturday, 2 p.m. Sunday, through June 19, Pennsylvania Playhouse, Illick's Mill Road, Bethlehem. Tickets: $18; $15, seniors and children under 19 Friday and Sunday only. 610-865-6665, http://www.paplayhouse.org .

Dave Howell is a freelance writer.