"American Idol" runner-up Katharine McPhee will make her studio acting debut as a pregnant hippie in an untitled comedy starring Anna Faris. McPhee, Emma Stone, Rumer Willis, Kat Dennings and comedian Dana Goodman have signed on to co-star in the feature, which is being directed by Fred Wolf for Columbia Pictures and Adam Sandler's Happy Madison Prods.

The script, by "Legally Blonde" writers Karen McCullah Lutz and Kirsten Smith, centers on a Playboy bunny (Faris) who gets kicked out of the Playboy Mansion and becomes the house mother to the lamest sorority on campus.

The casting fills in the major roles of the sorority sisters and solidifies the project as the first female-driven comedy to come out of the production company.

Stone will play the president of the sorority; Willis will play an insecure young woman who wears a back brace even though she could have had it removed years ago; Dennings will portray a women's studies feminist; and Goodman will play the sister who keeps switching majors and should have graduated years ago.

The comedy marks the second role McPhee has booked in as many months; in June, she nabbed a role in "The Last Caller," a dark romantic-comedy independent film.