"I have a very competitive side," admits Puccio, 21, who was introduced to climbing at age 13 along with her younger sister Casey by their mother. But it was Casey, at first, who was the better climber. "She was nine," says Puccio. "I couldn't have my little sister beat me. It drove me." And how. At age 16, Puccio won the first professional-level competition she entered, the 2006 American Bouldering Series Open National Championships. Since then, she's established herself as one of the top American competition climbers, winning a string of ABS titles and, in 2008, the International Federation of Sport Climbing Bouldering World Cup at the Teva Mountain Games, in Vail. "Some people don't like climbing in front of a crowd," she says. "But that's why I compete. I love feeding off the energy." Not that she can't perform on a lonely crag. On routes in Colorado, California, and Texas, Puccio has notched seven V12's, one of the hardest boulder problems a woman has sent. "I'd love to climb some V13's, V14's," she says. She already has a heavily overhung problem scoped out near her home in Boulder, Colorado, that could rate a V13. "With men, they're up to, like, V16," she says. "Women can get to that level, too. It's just that there aren't that many trying. At least not yet."