Google Inc. cofounder Larry Page is known for his vision, passion, and intelligence. Yet there is concern that his other known traits - aloofness, a rebellious streak, and an affinity for pursuing wacky ideas - might lead the company astray. Page takes over as chief executive officer Monday as fast-rising rivals and tougher regulators threaten Google's growth.
Investors used to Google's consistency in exceeding financial targets worry that new leadership will bring more emphasis on long-term projects that take years to pay off. And many people are not sure he has enough management skills to steer the Internet's most powerful company.
Page already has learned that smarts alone won't make him a great leader. Although Page impressed Google's early investors with his ingenuity, they still insisted that he step down in 2001 as Google's first CEO. He turned over the job to Eric Schmidt, who began working in Silicon Valley in the early 1980s while Page was still in grammar school.
Page's admirers say that at 38, he is more mature and less apt to be chronically late to meetings or tune out of conversations that do not stimulate his intellect - habits he fell into during his first stint as CEO.
"There are parts of being CEO that don't fit Larry's personality," said Craig Silverstein, the first employee Page and Google's cofounder, Sergey Brin, hired when they started the company in 1998. "You wear a lot of different hats when you're CEO. Some of them are very interesting to Larry and some of them, presumably, are less interesting."
True to his taciturn form, Page hasn't said much publicly since Google announced in January that he would replace Schmidt as CEO. Google said Page wasn't available for an interview.
Page, though, has left little doubt about his top priority: to dissolve the bureaucracy and complacency that accompanied Google's rapid transformation into a 21st-century empire. It is expected to end the year with more than 30,000 employees and $35 billion in annual revenue.
In Page's mind, Google needs to return to thinking and acting like a feisty start-up. Rising Internet stars such as Facebook, Twitter, and Groupon are developing products that could challenge Google and make its dominance of Internet search less lucrative.

Page has drawn comparisons to two high-tech geniuses who are even more accomplished: Microsoft Corp. cofounder Bill Gates and Apple Inc. cofounder Steve Jobs. Like them, Page invented and cultivated a product that changed the world.
But Page has yet to match them in this respect: As CEOs, Gates and Jobs brought out the best in the companies they created, delighting stockholders as their investments soared.
Page has wanted to control his own destiny, and legacy, since reading a biography of inventor Nikola Tesla before he was even in high school. Tesla wasn't rewarded or widely recognized for his breakthroughs in X-rays, wireless communications, and electricity. Page didn't want that to happen to him as an entrepreneur.
So Page embraced the chance to be Google's CEO when the company started in a rented garage not far from its current headquarters in Mountain View, Calif. It also helps explain why he and Brin created a separate class of stock with greater voting power so they and Schmidt could remain in charge after Google went public in 2004. Page's stake has made him one of the world's wealthiest people with an estimated fortune of $20 billion.
Hoping to smooth the transition to a new CEO, Google is keeping Schmidt, 55, as executive chairman and chief liaison with lawmakers and regulators around the world. It is an important job as Google faces scrutiny over its ambitions to enter new markets. Brin, 37, intends to focus on long-term projects, leaving Page to manage daily operations.
Schmidt guided Google through an uninterrupted stretch of prosperity that has topped the performances of other technology trailblazers, including Apple and Microsoft, at similar stages of their corporate lives.
Page is better prepared to be CEO after a decade as Schmidt's apprentice, said Douglas Merrill, who worked with both executives before leaving Google in 2008 as vice president of engineering.
"Larry has grown over time," Merrill said. "He has learned how to make projects work. He has learned how to make sure things happen on time and in a predictable fashion. Larry is a sort of a learning machine."