Grammy Award-winning 'American Idol' winners Kelly Clarkson and Carrie Underwood to perform on series finale

Three-night grand finale week kicks off with 'American Idol: American Dream,' a 90-minute retrospective, Tuesday, April 5

Surprises and special appearances on the two-part grand finale of 'American Idol' Broadcasts live from Dolby Theatre Wednesday, April 6, and Thursday, April 7, on FOX

"American Idol," the cultural phenomenon that changed the face of television and created some of today's biggest music stars, will kick off a three-night grand finale week on Tuesday, April 5 (8-9:30 p.m. ET/PT), with "American Idol: American Dream." The can't-miss, 90-minute retrospective will feature host Ryan Seacrest, current and former judges, former "American Idol" contestants and the behind-the-scenes team sharing its personal "American Idol" memories, as staffers reflect on what the show has meant to them and how it became the groundbreaking series that it is today. 

In addition to Seacrest, original "American Idol" judges Simon Cowell, Paula Abdul and Randy Jackson offer never-before-revealed stories about how "American Idol" came to be. This is a very special, inside look at the journey that "American Idol" has taken viewers on during its 15-season run.

The following night, America's most crucial - and last-ever - vote will take place when the remaining finalists battle it out live from Dolby Theatre on Wednesday, April 6 (8 p.m. live ET/tape-delayed PT). "American Idol's" two-part grand finale will be filled with surprise appearances and star-studded performances, including winners Kelly Clarkson and Carrie Underwood, who return to the "American Idol" stage one last time to perform on Thursday, April 7 (8-10:06 p.m. live ET/tape-delayed PT). The farewell celebration will continue, as "American Idol" pays tribute to the past 15 seasons, the talented contestants and the millions of fans who called, tweeted, texted and championed their favorites, before the 15th and final "American Idol" is crowned.

In addition to Clarkson and Underwood, Thursday's final episode will have all-star performances by Ruben Studdard, Fantasia, Taylor Hicks, Jordin Sparks, David Cook, Kris Allen, Lee DeWyze, Scotty McCreery, Candice Glover, Caleb Johnson, Nick Fradiani, Ace Young, Allison Iraheta, Amber Holcomb, Blake Lewis, Bo Bice, Brandon Rogers, Bucky Covington, Carly Smithson, Casey James, Chris Daughtry, Clark Beckham, Clay Aiken, Colton Dixon, Constantine Maroulis, Danny Gokey, Diana DeGarmo, Elliott Yamin, George Huff, James Durbin, Jessica Sanchez, Josh Gracin, Joshua Ledet, Justin Guarini, Katharine McPhee, Kellie Pickler, Kimberley Locke, Kree Harrison, LaToya London, Lauren Alaina, Melinda Doolittle, Pia Toscano, Sanjaya, Skylar Laine, Tamyra Gray and more, before Seacrest announces the results of America's votes and the final "American Idol" is crowned.