LOS ANGELES — In November, the actor Dax Shepard rolled up to a tree-shaded lot in the Los Feliz section of Los Angeles in a wood-grain 1994 Buick Roadmaster and parked in front of a single-door garage.
The yard was brown and dusty, with trucks out front and a portable toilet on the premises. His house was under construction. But we weren’t going there.
Instead, Mr. Shepard, who is 44 and rangy, tramped up a set of stairs outside the garage and unlocked the door to a cozy space with slate blue walls and the odd wire dangling from the slanted ceiling.
A long couch sat opposite a leather recliner and a daintier, midcentury-style seat. Three microphones stood nearby.
Before we sat down, Mr. Shepard wanted to know: Would I like coffee? I said that I’d already had tea that morning, and besides, I was trying and routinely failing to honor my doctor’s suggestion to drink less caffeine. Filling the coffee maker with water for himself, he asked: Did I have addictive tendencies?
Such casually blunt questions are a hallmark of “Armchair Expert,” Mr. Shepard’s interview podcast, which premiered in 2018. The episodes feature a mix of Hollywood names (Will Ferrell, Gwyneth Paltrow, Ellen DeGeneres, Emilia Clarke), authors (Elizabeth Gilbert, David Sedaris, Gillian Flynn) and specialists in various fields (Richard Dawkins, Esther Perel, the California surgeon general Nadine Burke Harris, Bill Nye).
The actress Kristen Bell, who is Mr. Shepard’s wife, was the show’s first guest.
Mr. Shepard — known for his roles on “Parenthood” and the new sitcom “Bless This Mess” — is the face and primary voice of the podcast. Monica Padman, a 32-year-old actress, is his quieter co-host; she also handles the behind-the-scenes work of wrangling guests and editing interviews.
The show, Mr. Shepard said, was never meant to be groundbreaking; long-form interviews have existed practically since the dawn of radio.
But he liked going on other people’s podcasts — how the intimacy and extended format granted more depth than seven minutes on a late-night show. When he appeared on “WTF With Marc Maron,” for example, he spoke openly about his sobriety. Afterward, he said, fans said that the conversation helped them on their own recovery journeys.
Now “Armchair Expert” competes with podcasts like Mr. Maron’s for listeners. The show closed out 2018 as the most downloaded new podcast on iTunes and won “Breakout Podcast” at the 2019 iHeartRadio Podcast Awards.
According to Mr. Shepard, it is often downloaded more than five million times in a week: roughly one million apiece from two new episodes, and another three million from the archive.
“It’s so wonderful to read that, to know that,” he said. “But then my brain shifts immediately into fear, like, how do we maintain that?”
“I’ve been in a bunch of things that work just enough,” he said. “So to have something that’s a hit for me also comes with fear as well as gratitude. I’m like, ‘This is wonderful. I don’t want to lose this. I would like this to go on for a long, long time.’”
Mr. Shepard was sitting in the attic’s leather recliner, rocking back and forth and sporadically tucking a long leg up under him. He was trying to police himself, he said, to make sure he didn’t sabotage the podcast’s success somehow.
On “Armchair Expert,” as in real life, Mr. Shepard is inclined toward self-analysis of his insecurities, motivations and shortcomings.
“It feels like Dax is a much more enlightened Howard Stern,” said Adam Grant, an organizational psychologist, whose interview aired in December. “You could say that he’s the poster child for an alternative to what sometimes gets called ‘toxic masculinity.’ I’m not a fan of that term — I much prefer the social science of what’s called ‘precarious manhood’ — but I think he’s a role model for how not to be someone who’s constantly trying to prove your manhood.”
Mr. Shepard’s frequent expressions of vulnerability — about his road rage, about his vanity, about being molested as a child — encourage his interview subjects to feel comfortable sharing something of themselves.
“His best quality in interviewing is making sure you don’t feel alone and naked out there,” said the actress Lake Bell, Mr. Shepard’s co-star on “Bless This Mess.” When she appeared on the show, she spoke about the traumatic birth of her son, which she hadn’t discussed publicly before.
“He creates a very safe space for an interviewee,” said Monica Lewinsky, who appeared on “Armchair Expert” in October. “There becomes something about Dax and about the way he deals with his own history which makes me want to meet him at his level of vulnerability.” (A fan of the show and a connoisseur of crystals, she brought green apophyllite as gifts for Mr. Shepard and Ms. Padman.)
It helps, Mr. Shepard said, that he and Ms. Padman give guests the option to cut portions of the interview after recording, should they regret something they said. Interviewees frequently take them up on this.
“I definitely had, as Brené Brown calls it, a ‘vulnerability hangover’ when I left,” Ms. Lewinsky said. “I panicked: ‘Oh God, was that O.K.? What did I just say? Will it be misinterpreted?’”
“You know how they pump oxygen into casinos?” she said. “It’s sort of like Dax and Monica pump some form of invisible truth serum into the air in the attic.”
Partway through our interview, Ms. Padman entered the room and sat next to Mr. Shepard. Concerned about the audio quality of my recording — “Can I be controlling and make a suggestion?” — Mr. Shepard relocated Ms. Padman’s chair between us so that she could be closer to the microphone. As we talked, he occasionally kicked a leg up to rest on the wooden arm of her chair.
The two have a close, almost familial relationship: First hired as a babysitter to Mr. Shepard and Ms. Bell’s children, Ms. Padman now works with both parents in a creative capacity, writing Ms. Bell’s awards-show monologues and reading commercial scripts to ensure that they’re written in the actress’s voice.
The affection between the hosts comes through most clearly during the “fact check” that they record after each interview, in which the two banter and debate — their favorite hobby — while Ms. Padman corrects various claims made throughout the interview.
When the comedian W. Kamau Bell recorded a live podcast with them in San Francisco, he got the sense that every audience question boiled down to some form of: “Can I move in with you and Kristen Bell and Monica?”
“A big part of the appeal of that show is that it scratches the same itch that a reality show scratches, without going down that tortured alley,” Mr. Bell said. “You’re in the middle of their relationship, and Kristen Bell is kind of like Kanye West on ‘Keeping Up With the Kardashians,’ where he’s just outside somewhere.”
Much of the work that Ms. Padman does on the show — the fact-checking, the editing, the scheduling — takes place off-mic. When they first started recording the podcast, she worried about getting enough airtime.
The anxiety, she said, grew out of a desire for approval from their guests, particularly those whose support could matter to her acting career, like Judd Apatow.
But, she said, “I don’t need to prove myself to any of these people. I can just be.”
Observing interviews from this slight remove, Ms. Padman sees herself as a proxy for the listener. She asks the follow-up questions that people may be curious about and makes sure to circle back to threads that get dropped midway through a conversation. She is always editing in her head. And, Mr. Shepard said, she holds him accountable.
“Monica will call me out when I’m being misogynistic or I’m being mildly racist or I’m being elitist or I’m being whatever — she will always call me out,” he said. “And I think she gives me latitude to be a real person who doesn’t do it right.”
At times, people have questioned their judgment. When the hosts invited Casey Affleck onto the podcast, some listeners criticized Mr. Shepard and Ms. Padman for giving a platform to the actor, who in 2010 was sued by two women for sexual harassment on the set of one of his films. (Both cases were settled out of court.)
In his interview, Mr. Affleck spoke in support of the #MeToo movement and discussed the difficulty of that period of his life.
Mr. Shepard was hesitant to discuss the backlash over that episode. He wasn’t afraid of a quote from his conversation with Mr. Affleck being pulled out of context, because the entirety of it is available to the public.
But to respond to it for this article would risk having his thoughts distilled into one sentence that could pour gas on the whole thing, he said. Still, he talked it out.
“We’re not a show that levies verdicts,” Mr. Shepard said. “We’re a show that lets someone tell their experience.”
He disagrees with the notion of “platforming” on the basis that it implies a person’s ideas are so persuasive that they shouldn’t be heard at all. Given the opportunity, Mr. Shepard said, he would gladly interview a serial killer — a bad analogy, he admitted, because it implies that he believes Mr. Affleck is somehow culpable, and he has no position either way on that matter.
“But I would interview a serial killer in two seconds,” Mr. Shepard said. “And my interview with a serial killer wouldn’t be, ‘You’re so bad. You know, you’re bad. You’re really bad. Have you thought about how bad you were?’ I would want to know what the point of view of a serial killer is. I want to hear their story.”
There’s no long-form interviewer he respects more than Howard Stern. On a technical level, Mr. Shepard said, “he’s just so calm, so confident, so prepared, so open to wherever it goes, never panicky.” And he admires Mr. Stern’s willingness to make apologies on air and soften the shock-jock persona that made him famous.
They have met and corresponded, but Mr. Shepard has refused to ask him to be on the show because he doesn’t want to feel like Mr. Stern is doing him a favor.
Mr. Shepard has trouble accepting help, he said, and fantasizes that one day Mr. Stern will ask to come on the podcast of his own volition.
“In all truth, I want just what Stern has,” he said. Ideally he would come in more often than he does now “and just sit in here and talk with Monica and other people.” He thinks he would prefer that over acting, he said, or, really, “anything else.”