Actor Zac Efron is leaving his High School Musical days behind him to hit the books at a California university. The 20 year old has reportedly signed up to study at the University of Southern California early next year. Efron initially applied to the school in 2006, deferring his admission to focus on his acting career and the hit teen musical franchise, according to U.S. magazine Star. A source tells the tabloid: "Zac wants to earn a college degree. Despite his success as an actor, it's one of his goals." Earlier this week, the pin-up insisted he's a college natural - because he's a self-proclaimed nerd. He said, "I got good grades at school - in fact, you'd have called me a nerd."