IT'S MEREDITH AND DEREK'S WEDDING DAY, ON ABC'S "GREY'S ANATOMY"

"Grey's Anatomy" Celebrates its 100th Episode with an Event No Fan Should Miss

"What a Difference a Day Makes" � As Meredith, Derek and all of their friends prepare for the big wedding, a group of college students, injured in a car crash as they were heading to their graduation ceremony, is admitted to the ER. Meanwhile, Izzie fears the worst when she begins experiencing familiar symptoms, on "Grey's Anatomy," THURSDAY, SEPTEMBER 10 (9:00-10:02 p.m., ET) on the ABC Television Network. (Rebroadcast: OAD: 5/7/09 )

"Grey's Anatomy" stars Ellen Pompeo as Meredith Grey, Patrick Dempsey as Derek Shepherd, Sandra Oh as Cristina Yang, Katherine Heigl as Isobel "Izzie" Stevens, Justin Chambers as Alex Karev, T.R. Knight as George O'Malley, Chandra Wilson as Miranda Bailey, James Pickens, Jr. as Richard Webber, Sara Ramirez as Callie Torres, Eric Dane as Mark Sloan, Chyler Leigh as Lexie Grey and Kevin McKidd as Owen Hunt.

Special guest star is Jeffrey Dean Morgan as Denny. Guest starring Jessica Capshaw as Dr. Arizona Robbins, Amy Gumenick as Becca and Roberto Urbina as Jordan.

"What a Difference a Day Makes" was written by Shonda Rhimes and directed by Rob Corn.

"Grey's Anatomy" is broadcast in 720 Progressive (720P), ABC's selected HDTV format, with 5.1-channel surround sound and Spanish audio via SAP. This program carries a TV-14,D,S parental guideline.

For more information on "Grey's Anatomy," visit ABC.com.