It's official: Zac Efron has committed himself to a new romantic relationship, according to This time, it's his first leading-man role in New Line's fast-tracked love story, Seventeen.

Capitalizing on the back- to-back successes of the big-screen musical Hairspray and small-screen sensation High School Musical, Efron finalized negotiations yesterday to headline the Big-like dramedy in which a 36-year-old man, in need of a major life do-over, wakes up in the body of a studly high school senior (Efron).

Efron had been in talks to make the film since February. The role reunites the HSM heartthrob with his Hairspray director, Adam Shankman, who is producing (but not helming) along with his sister, Jennifer Gibgot. ''It's a very multilayered role, which is what attracted Zac to this idea,'' says Gibgot, who has been working with Efron to shape the role that could expand Efron's fanbase beyond the screaming tween crowd. ''It's a good transitional movie that will appeal to his audience and hopefully bring in more adults,'' she says.

No director has been announced yet, but the producers hoped to have a commitment before the weekend. The film could start shooting as early as November. Efron has been in talks to do a remake of Footloose.