'Don't Think Twice' is a love letter to improv (R)

Actor and standup comic Mike Birbiglia (“Orange is the New Black”) made his directorial debut with 2012’s “Sleepwalk with Me,” an intelligent look at the life of a comic in his 30s whose once-promising career had sputtered.

Birbiglia, who also writes and stars in his films, stays on familiar ground with “Don’t Think Twice,” an immensely enjoyable, warmhearted and gentle showbiz dramedy about the members of an acclaimed, if financially strapped, comedy improv group in New York who are about to lose their theater — and one of their most bankable members.

Called the Commune, the six-member group performs gorgeous old-school improv at a small comedy club that’s venerated as the place where some of TV’s biggest comics got their start. The group’s work is impressive, fresh, alive — and beautifully performed by an ensemble cast that includes Keegan-Michael Key (“Key & Peele”), Gillian Jacobs (“Community”), “Inside Amy Schumer” writer-producer Tami Sagher and Kate Micucci (one half of the musical comedy duo Garfunkel and Oates).

Each cast member creates a unique, deeply idiosyncratic and seriously neurotic character. They’re men and women who make no money from a profession they love.

Birbiglia plays the group’s 36-year-old elder statesman Miles, a sought-after acting teacher who has never been able to make the big-time as a performer. He’s full of angst and vinegar, spouting insults at former students who’ve made it in Hollywood or landed a starring role on the “Saturday Night Live”-ish Weekend Live.

The film’s major conflict comes when Jack (Key) and his Commune co-star and lover Samantha (Jacobs) are both offered auditions at Weekend Live. Armed with a killer Barack Obama impersonation, the ambitious Jack jumps at the chance. Samantha is a dreamer and an improv purist who dreads the idea of going mainstream.

“Don’t Think Twice” does a nice job of satirizing this corner of the showbiz world. More than that, it’s a celebration of improv, a uniquely American art form.

Like jazz, improv values free, associative thinking over the rehearsed and the repetitious. As Samantha’s wonderfully crafted voice-over explains, an improv creation is ephemeral, a pure product of the now.

Birbiglia proves himself to be a sure hand when it comes to his performers — who are superb across the board. But Key and Jacobs deserve extra props for their sensitive portrayal of a loving couple torn apart by ambition and the mysterious workings of fate.

Cast: Mike Birbiglia, Keegan-Michael Key, Gillian Jacobs, Kate Micucci, Chris Gethard, .

Writer-director: Mike Birbiglia.

A Film Arcade release. Running time: 92 minutes. Vulgar language, drug use. In Miami-Dade: O Cinema Wynwood, South Beach; in Broward: Gateway. The 9:15 p.m. Friday and Saturday screenings at O Cinema will be preceded by short performances from the improv troupes Just the Funny and Villain Theater. Click here for info.