Mike Calabrese was standing backstage a year ago at New York City’s Town Hall before a concert to celebrate the music of the Coen Brothers film Inside Llewyn Davis, when the Lake Street Dive drummer experienced the epic pinch-me moment of his career.

“I looked around and I was standing next to Jack White, while he picked a fiddle tune with Keb’ Mo’, after meeting Joan Baez and Elvis Costello,” Calabrese recalls. “It was this insane little hang. To feel welcome there and to have your hand shaken by Marcus Mumford and have him be like, ‘Hey, I really dig you guys’ stuff’ — you’re sort of like, ‘Huh? Where am I right now?'”

Just two years ago, Lake Street Dive was touring the country in a van in support of their 2011 self-titled release. The quartet met in 2004 as students at the New England Conservatory in Boston. Guitar/trumpet player Mike “McDuck” Olson recruited Calabrese, upright bassist Bridget Kearney, and vocalist Rachael Price for a country band, but they soon morphed into the harmony-driven soul/pop outfit they are today. The band didn’t take off in earnest, however, until Kearney departed the string band Joy Kills Sorrow, a 2012 Spoleto act, to focus on Lake Street Dive.

In 2012, the band released the EP Fun Machine, which included covers of George Michael’s “Faith” and Hall and Oates’ “Rich Girl.” A promotional video for the album, featuring Lake Street Dive’s jazzy take on the Jackson 5’s “I Want You Back,” went viral, topping two-million views. That exposure paved the way for the release of the 11-song Bad Self Portraits in February of this year.

“Everything happened really quickly,” says Calabrese, although he adds that they sat on Bad Self Portraits for all of 2013 while they cultivated an audience and “built hype really naturally” for the release.

Without support from a major label (they released BSP on the Boston indie Signature Sounds), Lake Street Dive have done pretty well for themselves. They’ve toured Europe twice in the last year, including sold-out dates to over 600 people in Copenhagen and London. Back home in America, they’ve retired the van in favor of a comfortable bus and the occasional air commute.

“It’s weird when our manager is like, ‘We need to get a business manager and a merch person and a tour manager and a monitor engineer and a front-of-house engineer, and we’re like, ‘Woah, what is happening?'” Calabrese admits. “We can’t always see the reason, but once we get someone, we’re like, ‘How did we ever live without them?’ We’re learning about the business as it comes at us, and it’s been a rush.”

Fortunately, the growing operation means that the band members can focus even more on what they do best.

“Everyone in the band is very responsible when it comes to their role in creating the greater good, and nobody wants to be the weak link,” Calabrese explains. “It’s like a marriage, or so I hear. It’s not about you; it’s about the thing that you’re in with someone else, so it’s all about the shared experience.”

Those experiences now include an August appearance on Conan (prompting the host to exclaim, “I am buying what you’re selling,” after their performance of “Stop Your Crying”) and a fall tour that’s seen them grow as headliners.

“I’ve always had faith in this band, but I never expected any of this to happen the way it has. I figured it would be a much slower process,” says Calabrese. “We’re so green — we never know what the next step is until it comes at us.”