The movie will star Tina Fey as a college admissions officer at Princeton who falls in love with a 17-year-old student.
Paul Rudd, who stepped in to replace Owen Wilson, will play a professor interested in the Fey character.
According to Deadline, Walger has signed on as a character named Helen, another college professor. Michael Sheen, Lily Tomlin and Wallace Shawn also star.
Paul Weitz, director of Little Fockers, About a Boy and In Good Company, is helming the project.
Admission is currently filming and is scheduled for a 2013 release.