In 1996, Landry came up with the idea of a stage presentation of the Capra story in the form of a 1940s radio broadcast and the doubly nostalgic concoction has grown into a national perennial.
Last year, 100 theaters around the country presented the show, this year that number is up to 150.
Local theatergoers will have a chance to see members of the original production do the show again when it is presented as a benefit for Music Theatre of Connecticut on Saturday, Dec. 15, at the theater, 246 Post Road East in Westport.
"It has been astounding and I am so grateful," Landry said in a recent interview of the way his show has taken off, as both a professional and community theater staple.
"It is a tough act to follow," he added of his other playwriting work.
The Landry version of "It's a Wonderful Life" is built on a largely forgotten aspect of commercial radio in the 1930s and 1940s, the presentation of popular contemporary films as radio plays.
Back in the day, audiences had a chance to hear condensed audio-only versions of everything from "Casablanca" to "Jezebel" (sometimes with the original stars, sometimes not).
A lot of the fun in the Landry version comes from the difference between what we see in the studio and what audiences out in radioland are hearing -- including the sources of all of those seemingly realistic sound effects.
"The great thing about (my play) is that it is kind of on autopilot now," Landry said of the way that word of mouth and the number of productions keep building each year.
The MTC production is special to Landry because of its ties to the first staging of "It's a Wonderful Life" and because director Kevin Connors' take on the show won the Moss Hart Award at the New England Theatre Conference.
In some places, the play has become an annual event, in others it has been produced in rotation with other such holiday stage classics as "The Santaland Diaries" and "A Christmas Carol."
"There's a hotel in St. Paul (Minn.) that has done it for a few years now, and others that have done it for six years," Landry said.
Last year, two of the most renowned regional theaters in the country -- Trinity Rep in Providence, R.I. and Long Wharf Theatre in New Haven -- mounted full-scale, professional productions of the play.
"This production is like coming home to me," Landry said of the Westport staging with his longtime colaborator Connors.
"I've had an association with these actors for a long time. As many different productions of this that I've seen, there is something so intimate and homespun about seeing it done at MTC," the playwright said of the less-than-100-seat venue.
"A space that size ramps up the emotions in every direction," Landry added.
IT'S A WONDERFUL LIFE
Music Theatre of Connecticut, 246 Post Road East, Westport. Saturday, Dec. 15, 2, 8 p.m. $75-$45. 203-454-3883. www.musictheatreofct.com.