When Rich Lesser took off for Beijing in May 2012, his plane wasn’t the only thing up in the air. He was a candidate to become CEO of the Boston Consulting Group, and BCG’s 750 or so partners (of which he was one) had until noon that day to cast their ballots for a new leader. Just hours before his flight touched down in China, a member of the flight crew delivered Lesser a note: He’d won, becoming the sixth chief executive in the firm’s 50-year history.
It was a sweet victory for Lesser, a bespectacled engineer-turned-Harvard-MBA who joined the “Big Three” consultancy in 1988. But the election process also says a lot about what sets the firm’s culture apart — and makes it a perennial top five on our Best Companies list.
Unlike its main rivals, BCG uses a “one partner, one vote” process, so each vote counts equally. That kind of democracy is appealing to people who value having a say in the firm’s future. “It’s really an opportunity to talk about where we’re going and what’s possible for BCG to achieve,” says Lucy Brady, a senior partner in Chicago and head of recruiting for North America.
The other side of that coin is that no one’s performance is beyond review. Everyone from associates to senior partners receives continual “feedback,” like the formal case reviews — an assessment of factors like communication and “acting as a role model” — after every project.
These critiques felt intrusive at first to Devesh Raj, a 13-year BCG veteran and the Americas leader for its technology, media, and telecommunications practice. As a doctoral student in physics at Yale, Raj was more accustomed to occasional check-ins with an adviser. But once he got used to the feedback, “I was addicted,” he says. “You realize it’s actually very hard to get good advice in the world.”
David Potere, a former U.S. Navy officer with a Ph.D. in demography, recounts how feedback and working with a BCG-provided life coach helped him adjust to his new corporate environs. “It’s definitely changed the way I communicate, the way I prioritize,” he says.
As Lesser steers the firm, how will he know he’s on the right track? Don’t worry, he says. It’s almost like he has a board of directors of nearly 800 people — who are, by the way, “not shy.”
Boston Consulting Group
100 Best Companies to Work For Rank: 4
Headcount: Around 9,000
Partners: Around 750
Offices: 78 in 43 countries
2012 revenue: $3.7 billion
This story is from the September 16, 2013 issue of Fortune.