Sticking to the old injunction to write about what you know, Mike Birbiglia, whose first film, “Sleepwalk With Me” (2012), was an extension of his own stand-up comedy routine, turns in his second to the story of an improv troupe facing internal stress and possible dissolution. “Don’t Think Twice” is, like his earlier picture, a relatively modest effort, but one that offers some real insight into the world of performers struggling for a degree of recognition most are unlikely to achieve.

The Commune, as the six-person group is called, has been working together for years at a small venue in New York City. But the place is about to be sold, and all the alternatives would be substantially more expensive. But there’s a further problem: talent scouts for a Saturday Night Live-style television program come to one of the shows, and ambitious Jack (Keegan-Michael Key) decides to take center stage to impress them. A couple of others are offered auditions along with him, but he’s the one who lands the star-making gig on the tube.

His colleagues congratulate him, of course, but there’s an obvious undercurrent of envy in the attitudes of the other five, only one of whom, Lindsay (Tami Sagher), needn’t worry about money because she comes from a wealthy family. Jack’s sudden rise will cause some consternation in Samantha (Gillian Jacobs), his partner at home as well as on stage, while sad sack Bill (Chris Gethard), who’s understandably depressed over the illness of his father, will join with Allison (Kate Micucci), an illustrator, in a turn toward writing rather than performing. Most affected, however, is Miles (Birbiglia), who’s watched from the sidelines as several of those he’s mentored have gone on to bigger things while he’s stuck teaching and soldiering on with decreasing hopes that his break will come.

In fact, Miles, like the other four, hopes that Jack will not only drop by occasionally to lend his star wattage to the act, but will be able to transmit samples of their writing to the TV program’s head honcho in the hope that he’ll be impressed and hire them, too. Of course, there’s only a slight chance of that happening, though when another of them is anointed along with Jack, it will cause the already frayed relationships within the Commune to deteriorate further.

The situation becomes more and more trying for Samantha, who grows desperate to keep things going even as the group falls apart, but especially devastating for Miles, whose constant failure to make it up the next rung of the ladder leaves him ready to throw in the towel. Happily there’s at least a turn for the better in his private life, as Liz (Maggie Kemper), an old high-school classmate, shows up to reconnect. Though unimpressed with his living arrangement—he’s still sharing an apartment with friends, dorm-style—she’s won over by his sensitivity to a difficult situation she finds herself in.

“Don’t Think Twice” gets the feeling of improv performance right—the scenes of the group tossing lines to one another to keep the rhythm alive as Joe Anderson’s camera whirls around them capture a sense of the risky nature of the enterprise—and the performers are all likable folk whom you can empathize with even when they occasionally do unsympathetic things (when Jack, desperate to score on the program, makes use of a routine the group had previously devised, one acknowledges the betrayal, but understands it). A cameo by Ben Stiller, whom they try to impress when he drops by for their act, plays to the desperation one can feel growing among the long-time colleagues. The picture does, to be sure, go soft at the end, following a dust-up at a Manhattan club with a coda in which old friendships are restored even in the shadow of grief. But the people are so agreeable that you’re unlikely to be too peeved. This is obviously not a big-budget production, but all the technical contributions are more than serviceable.

Most show business movies are about meteoric rises, often followed by a precipitous fall (and sometimes a recovery). Here’s one about the vast majority of performers, who toil endlessly with visions of stardom in their eyes, never to see them realized. Yet it’s not a depressing film, but a truthful one that suggests that sometimes smaller rewards are enough, and maybe better.