Olivia Wilde and Jake Johnson star in Joe Swanberg’s “Drinking Buddies.” Courtesy of Magnolia Pictures.

I’m always perplexed by critics who complain that nothing happens in Joe Swanberg’s films, as if a more straightforward plot structure would serve as an improvement. Swanberg’s films don’t have a “plot” (in the traditional sense) primarily because his characters have yet to write their own story. For the past decade, Swanberg specialized in exploring the lives of twentysomething drifters grappling with their evolving identities, experimenting with their sexuality and questioning their uncertain future. Oftentimes, these characters would be pushed by their elders (and, in some cases, their peers) to “get serious” about their employment, their relationships and their lives in general. And throughout it all, critics have urged Swanberg to do the same thing.

Perhaps these dissenters will be quick to praise Swanberg’s latest work, “Drinking Buddies,” simply because it’s his first film to have a sizable budget, A-list actors and cinematography courtesy of a Cannes prize-winner (“Beasts of the Southern Wild” DP Ben Richardson). Indeed, Swanberg told The New York Times that he considered this film to be his first feature, while referring to his previous work as “the best 10 years of practice that a filmmaker could have.” Yet that isn’t necessarily an admittance of artistic growth so much as it is an acknowledgement of a new era in his career. His recent, little-seen trilogy of sexually explicit mosaics, culminating potently in “The Zone,” were candid self-examinations in which Swanberg questioned his own filmmaking techniques and obsessions before (seemingly) abandoning them altogether.

However, the major change in “Buddies” is not so much in the style as it is in the narrative. With other major production tasks assigned to fellow collaborators (for perhaps the first time in his DIY career), Swanberg was able to concentrate solely on directing the picture while keeping his signature approach fully intact. Though the characters were fully developed beforehand, all of the dialogue and a number of key moments (such as an impromptu evening of skinny-dipping) were entirely improvised. Though some filmmakers have scoffed at this approach, equating it with a composer’s refusal to write notes for his orchestra, “Buddies” provides undeniable proof that Swanberg’s approach can capture a great deal of insightful nuances as long as his actors are game.

As a radiantly witty Chicagoan who engages in a flirtatious friendship with her buddy (Jake Johnson of “New Girl” fame) at a brewery, despite the fact that they both have significant others, Olivia Wilde delivers the sort of performance that reminds you why anyone considered her a star in the first place. Hollywood’s routinely underwhelming vehicles for the actress have left her looking airbrushed and wooden (remember her in “Cowboys & Aliens”? Neither do I). Under Richardson’s earthily sensuous gaze and Swanberg’s generously empowering guidance, Wilde finally blossoms. She’s not only funnier and looser than ever before, she also deftly conveys the confusion and vulnerability that fuels her character’s mixed signals. Anna Kendrick is equally effective as Johnson’s fiancée, who shares (in an exquisitely excruciating prolonged take) a hormonally perplexing snog with Wilde’s longtime boyfriend (a dryly funny Ron Livingston). No wonder Wilde cited this film as the best acting experience of her career. All of these actors are able to take ownership of their screen time in ways that would be impossible on a studio set. Though Wilde is more or less a household name, Swanberg is the first director to make her a star, just as he did with Greta Gerwig, Josephine Decker and Kate Lyn Sheil.

Since Swanberg’s films are nearly always painstakingly personal, his characters have aged right alongside him. Now as a 31-year-old happily married father, the director’s interest has shifted from post-collegiate angst to the lingering gray areas of young adulthood. The quartet of cordial bedfellows in “Buddies” are on the cusp of commitment yet not quite ready to take the leap. Swanberg has openly cited that Johnson and Kendrick’s characters are loosely based on himself and his wife, Kris, in the days prior to their marriage. “Buddies” acutely observes the pivotal moment in one’s life when the future ceases to be an abstraction and emerges as an inescapable fact. For the first time in a Swanberg movie, the characters “get serious” and the story reaches a rather satisfying (though still pleasingly ambiguous) conclusion.

It may not be as riveting as Swanberg’s 55-minute masterwork, “Marriage Material,” or a groundbreaking game-changer like his debut effort, “Kissing on the Mouth,” yet “Buddies” is still a thoroughly enjoyable vignette from a filmmaker with no desire to compromise his integrity to make an extra buck. He’s achieved success by remaining true to himself, and there’s nothing more triumphant than that. And if you doubt my lofty claims regarding “Kissing,” check out the much-praised sex scenes on HBO’s “Girls,” created by Swanberg super-fan Lena Dunham (soon to star in Swanberg’s next picture, “Happy Christmas”).

“Drinking Buddies” is available on VOD and will open at Chicago’s Landmark Century Centre Cinema on August 23rd.