Kaitlin Olson (It's Always Sunny in Philadelphia) has boarded Spyglass Entertainment's romantic comedy Leap Year, starring Amy Adams, Bill Nighy, Matthew Goode and Adam Scott.

According to The Hollywood Reporter, the story centers on an American woman (Adams) who goes in search of her boyfriend in Ireland so she can propose to him on Leap Day, Feb. 29 -- which, according to tradition, requires him to say yes. Olson will play Libby, the married older sister of Adams' character, Anna.

Anand Tucker (Shopgirl) is directing a screenplay by Harry Elfont and Deborah Kaplan (Made of Honor). Benderspink is producing.

Shooting is underway in Ireland.

Leap Year was released January 8th, 2010 and stars Amy Adams, Matthew Goode, Adam Scott, John Lithgow, Noel O'Donovan, Tony Rohr, Pat Laffan, Alan Devlin. The film is directed by Anand Tucker.