Quick Answer: Mike Birbiglia's Don’t Think Twice is a story about improv comedy, acted mostly by improv veterans. Birbiglia drew on his own experiences with improv and stand-up to inform the script. The only cast member who'd never done improv before was Gillian Jacobs, who received a crash course in the practice before the filming. The cast rehearsed for two weeks all together in New York before giving public performances at the Upright Citizens Brigade Theater and Magnet Theater. Jacobs admitted, "It was truly terrifying to go out and perform in front of audiences after having studied improv for only two weeks!”

Anyone familiar with the worlds of New York's Upright Citizens Brigade Theater or Chicago's Second City Theater will recognize much of Mike Birbiglia’s Don’t Think Twice (2016). The director's second feature is a story about improv comedy, acted mostly by improv veterans.

Don't Think Twice follows a six-member New York improv ensemble called the Commune. Working menial day jobs but buoyed by their comedy practice and their tight friendship on and offstage, the Commune members take part in an almost utopian group existence befitting of their name —that is, until scouts from popular sketch comedy TV show Weekend Live attend a performance. When only two of the six cast members get noticed, the group dynamic starts to splinter, and heavy questions of failure and success loom large.

Birbiglia has drawn extensively on his own experience in improv and stand-up to inform the film. The actor/director feels that improv is a practice that has helped shape him into a disciplined filmmaker. Best known for his acting roles in Orange is the New Black (2013) and Trainwreck (2015), Birbiglia made his directorial debut with Sleepwalk With Me (2012), an adaptation of his one-man comedy show. “Directing Sleepwalk with Me was the hardest thing I’d ever done in my life, and I toured the country doing standup for 15 years,” Birbiglia said in the film’s press notes. “In the aftermath, I took inventory of the process and how I had learned to be a director. I realized what got me through was the training and the philosophy of improvisational theater, which I’d learned in college and at the Upright Citizens Brigade Theater. So I started doing improv every week. ” In addition to Sleepwalk with Me, Birbigli has created and starred in the one-person off-Broadway shows My Girlfriend’s Boyfriend and, currently, Thank God For Jokes (“the best night I've spent in a theater in a very long time,” according to Neil Genzlinger of The New York Times.)

Most of the cast members also have real-life experience in the most famous improv spots in the US: Keegan-Michael Key (Jack) is an alum of the iconic Second City Theater in Chicago. Tami Sagher (Lindsay), who has written for Girls (2012 - ) Broad City (2014 - ) and Inside Amy Schumer (2013 -), was the youngest player ever on the Second City mainstage. Chris Gethard (Bill) is a well-known member of New York’s Upright Citizens Brigade Theater and toured with Birbiglia while the director was developing the script.

In order to create the genuine feel of a tightknit improve group, the cast rehearsed and bonded for two weeks all together in New York. Gillian Jacobs (Sam) — perhaps the most well-known of the film’s actors to a wide audience for her roles on Love (2016) and Community (2009 - 2015) — is the only lead who’s a newcomer to improv, and Kate Micucci (Allison) had not practiced it in years. Improv coach Liz Allen helped Jacobs and Miccucci get up to speed, and eventually the six gave public performances as The Commune at Upright Citizens Brigade Theater and Magnet Theater. Jacobs said in the film’s press notes that while her co-stars were incredibly warm and generous, "It was truly terrifying to go out and perform in front of audiences after having studied improv for only two weeks!”

Jacobs and Birbiglia at the SXSW Premiere of Don't Think Twice (2016), Photo by Mike Windle via Getty Images

During a year spent writing the screenplay for Don’t Think Twice, Birbiglia invited people over to his house to read the script out loud — these guests included Ira Glass, who has worked with Birbiglia on This American Life since 2008, was a co-writer and producer on Sleepwalk with Me, and is a producer of Don’t Think Twice. Glass observed in the press notes, “Mike developed this screenplay the way that a standup develops material. We just did one reading after another after another after another in his living room.”

Birbiglia himself plays the leader of the group. Interestingly, the director cast himself as the least appealing, least talented of the six players. “Miles has no grasp of reality and thinks more of himself then he should. He’s the least-likable, most deluded of the group,” Birbiglia said. “In the readings at my house, sometimes I’d play Miles, sometimes I’d play Jack, sometimes I’d play Bill. And I got more laughs reading Miles. There’s something about the bitterness of the character that I wore in a natural way.”

The film’s three improv scenes were filmed in front of a live audience at The Lynn Redgrave Theater (the setting for Birbiglia’s Sleepwalk With Me and Thank God For Jokes.) To create the sense of being onstage with the performers, Birbiglia and cinematographer Joe Anderson chose a Steadicam, operated by Mike Fuchs, who moved around onstage, remaining at the cast's eye level. “Mike was like a seventh actor, in a way; he was improvising as well,” Birbiglia said. “Joe would tell him to pick off this bit of action or pan this way or move in that direction. It gives the scenes a documentary feel without compromising the elegance of the shot.”

According to cast member Key, the idea of improv applies on multiple levels in Don’t Think Twice. “The movie is about growth and stepping into the unknown, which of course is what improvisation is," Key said in the press notes. "The micro of the movie, the plot, and the macro are the same. It’s a very full and thoughtful piece and I’m so happy to be a part of it. I think that everyone will enjoy it because it’s about human themes. You don’t need to know what improv is to get it.”

Indeed, while Don’t Think Twice is grounded in the very specific world of New York City improv, its themes of failure, life's unfairness, and the painful realities of change are universal. Within their professionally funny world, the characters experience what we have all lived through yet too rarely get to see reflected back at us with honesty onscreen.