In a recent issue themed “The Agile Executive,” the Harvard Business Review offered a piece of advice for C.E.O.’s: hire a chief of staff. Somewhere between an executive assistant and a C-suite exec, a chief of staff is someone who “should handle several principal duties, all focused on making time, information, and decision processes more effective,” explains Dan Ciampa, a former consulting-firm C.E.O. turned C.E.O. adviser.

Anything more concrete in the way of day-to-day responsibilities is hard to glean. And yet, despite most people’s not having any idea what a chief of staff does, the job has become ubiquitous.

In the past five years, Forbes has published 11 stories encouraging people to either hire or become a chief of staff. In 2021, the University of Oxford’s Saïd Business School started the Chief of Staff Executive Education program, a four-day crash course for “the gatekeepers to Fortune 500 companies.”

Despite most people’s not having any idea what a chief of staff does, the job has become ubiquitous.

There are at least five podcasts devoted to the profession as well as several Substacks—including “Chief of Staff Learnings,” “Ask a Chief of Staff,” and “Chief of Staff Monthly.” Last August, MasterClass, which itself employs a chief of staff, published a story detailing the skills necessary to become one.

Billion-dollar companies, from Apple and Amazon to Berkshire Hathaway and JPMorgan Chase, employ chiefs of staff, as do JetBlue, Bridgewater, LVMH, and Netflix. So do smaller companies—Goop, Barry’s Bootcamp, and Erewhon all have them. Equinox and Grindr are currently trying to fill the role. Start-ups with barely any staff to be the chief of have them, as do the unemployed spouses of many C.E.O.’s.

“Creative director was the hot job 10 years ago,” says Doug Leonard, the chief of staff to SoulCycle C.E.O. Evelyn Webster, and a former chief of staff at American Express. “Now [it] feels like chief of staff has moved into that territory.”

It’s “a term that sounds interesting,” Leonard says, “but not everyone knows what it does.”

From the Military to Politics to … Everything Else

Initially, the chief of staff was a military position. The year 1903 marked the army’s inaugural chief of staff, the country’s highest-ranking military officer. His many obligations included supervising the army staff and developing, planning, and executing military programs.

In 1946, Harry S. Truman hired John R. Steelman, creating the country’s best-known chief of staff: the White House’s. The White House chief of staff is meant to serve as a liaison between the president’s office and Congress, “directing, managing and overseeing all policy development, daily operations, and staff activities for the President,” as the Clinton White House described it.

Shortly after Truman first brought the chief of staff from the military to politics, vice presidents, senators, governors, and mayors started hiring their own. The job then trickled into private companies, especially tech start-ups in Silicon Valley, around the 90s.

Like a chief of staff to a senator, a chief of staff to a C.E.O. is meant to “always keep an eye out on how to protect, preserve, and enhance [a] boss … but also the company”—or the district, city, state, or country—says Michelle Scannell, who worked as a chief of staff to Sharon Cissna, the former Alaska state representative, and then as a chief of staff at various tech start-ups.

Now the perk of a chief of staff is no longer reserved for C.E.O.’s. In 2014, “the top few executives at a firm would have a chief of staff,” says one chief of staff at an asset-management company in charge of more than a trillion dollars. In the past five years, she noticed that second-tier executives started hiring them, too. The number of chiefs of staff at her company has ballooned from about 3 to 15.

And yet, despite this boom in popularity, an exact description of the chief-of-staff role still does not exist. Blogs devoted to the position have described it as “an air traffic controller,” a “Jack or Jill of all trades,” an “extension of the C.E.O.,” and as someone who plays both “bad cop and good cop.” This can mean serving as a “body man” who “helps manage the flow of people who have approached the executive” after he or she speaks at a conference, wrote Maggie Hsu, the former chief of staff to the C.E.O. of Zappos, on her blog.

Goop, Barry’s Bootcamp, and Erewhon all have them. Start-ups with barely any staff to be the chief of have them, too.

“Every single [chief of staff’s] job is completely different,” says Jin Calello, a chief of staff at Verve, a talent agency in Los Angeles.

“Your responsibilities often can be anywhere along the spectrum of a glorified executive assistant [to] an under-glorified C.E.O.,” says Steven Greitzer, the former chief of staff at Quibi, Jeffrey Katzenberg’s short-lived video-streaming platform.

While the specifics of the job remain elusive, the appeal is clear. Beyond the salary, which hovers around $152,000 on average, it offers access to the C-suite. “At best, the chief-of-staff role is like a quasi-apprenticeship with a C.E.O. or with various members of the leadership team,” Greitzer says. “I got to be in the room as major strategic decisions were being made.”

The role “is typically viewed as a leadership-development program,” says Doug Leonard. “It’s a place for you to send your high-performing, high-potential talent to go through—almost a two-year boot camp to make them ready to be one of your future executives.”

Or, as one person who worked as a chief of staff at an early-stage tech start-up explains, “it’s like getting your street M.B.A.”

“How many 26-year-olds are sitting in a room with the C.E.O. of one of the largest banks in the world, or even, for that matter, diplomats and presidents?” asks the chief of staff at the asset-management firm.

“The color orange did not exist in the English language—at all—until explorers brought back oranges, and then all of a sudden it started popping up,” says Michelle Scannell. “In many ways, the chief of staff in the private sphere is like the color orange. Everyone seemed to know that they needed something. They just didn’t know the vocabulary.”

Jensen Davis is an Associate Editor for Air Mail