Reese Witherspoon has signed on to star in an untitled James L. Brooks-directed comedy for Columbia Pictures.

According to Variety, Brooks has directed only five films during his career and hasn't helmed one since 2004's Spanglish, mainly because he has been holed up writing the screenplay for the film, which is described as an ensemble project that boasts at least three major characters -- a hallmark of such Brooks films as Broadcast News and "Terms of Endearment."

Witherspoon is the only lead to sign on so far.

Logline is being kept under wraps on the film, which has the working title How Do You Know?

Studio is eyeing a March start date.