When Angela Hicks first met venture capitalist Bill Oesterle in 1994, she was a frumpy, introverted economics major at DePauw University who wore Coke-bottle glasses and showed up for a summer internship interview wrapped in a baggy sweater. Oesterle brought her on as an intern anyway because he thought the quiet youngster had a spine. When she graduated a year later, Oesterle persuaded Hicks to turn down a job at Arthur Andersen to work for him. Her job involved compiling a list of reputable plumbers, electricians and roofers in Columbus.
Today, Hicks is a celebrity who is lauded on TV alongside the likes of Sandra Day O’Connor and Condoleezza Rice. Her list — Angie’s List — has morphed into a publicly-traded company with 1,300 employees, more than 2 million members in 200 markets who pay to access reviews of home improvement professionals, mechanics, doctors, and dentists. While Hicks, 40, is the company’s public face, her erstwhile mentor, Oesterle, 47, is its behind-the-scenes CEO. And the company owes its success to the unusually strong bond that the two forged over nearly 20 years working side by side through ups and downs. “I trust Angie implicitly with anything,” says Oesterle. Of his mentorship, Hicks says: “As a young person, I was afraid of my own shadow and had never thought of being an entrepreneur. He taught me that, he taught me to be a manager.”
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The teaching went both ways. In the early days, there was nothing certain about Angie’s List (ANGI). Hicks worked around the clock on a card table in a rented 100-square-foot office she shared with an accountant and a builder. Members were slow to join, and Hicks did whatever it took to get the word out: from borrowing Oesterle’s neighbor’s Christmas card mailing list, to selling door to door on weekends, and even sitting on the back of a car during a 4th of July parade to wave at the crowd. With some regularity, she would break down in tears in front of Oesterle, then immediately promise not to quit. By 1998, the company was operating in four markets, and Hicks went off to Harvard Business School. After she graduated, it was Oesterle’s turn to have doubt about the company’s viability. “I said, ‘I don’t care, I’m coming back,’ ” Hicks says.
With Oesterle in charge of charting the vision and strategy for the business, Angie’s List began gathering momentum around 2004, raised tens of millions from venture capitalists, and went public in 2011. The company is expected to become cash-flow positive this year, and its stock is trading near an all-time-high. Though Wall Street may have warmed to Angie’s List only recently, thanks to Hicks, the company has been a darling of Main Street for years. On a recent trip, Hicks and Oesterle were eating at LaGuardia Airport while waiting for a plane when a fellow passenger recognized Hicks. “Hi Angie! I love you, Angie,” the man yelled. Then he turned to Oesterle and said: “Who the hell are you?” Oesterle was unperturbed by the slight. “My chest was bursting with pride,” he says.
A shorter version of this story appeared in the July 22, 2013 issue of Fortune.