In a new twist, former contestants Helio Castroneves, Kelly Osbourne, Melanie "Mel B" Brown, Drew Lachey, Gilles Marini, and Emmitt Smith will individually sit in to judge the dances they inspired.
"We know what it feels like to be judged when we were on this show, so you never want to say anything. But we have to be honest," said Osbourne, who will be judging her favorite contestant, Bristol Palin.
"I just have such a soft spot for her. I think she's what the show's all about and she's dancing with her heart, and that's what it's about," she said.
"It's so great to see everyone -- the family -- having fun. I'm actually scared to be a judge, I hate to be judging," said Castroneves. "We have to be fair, but hopefully it will be a lot of fun."
There will also be a team Cha Cha number, with the couples on the losing team up for elimination on Tuesday night.
Olympic and "Dancing With the Stars" champs Kristi Yamaguchi and Apolo Anton Ohno were brought in to help the teams. Yamaguchi worked with Bristol Palin, Rick Fox and Kyle Massey, while Ohno worked with Jennifer Grey, Brandy and Kurt Warner.
The audience will be filled with dozens of other contestants from past seasons Monday, including John O'Hurley, Jerry Springer, Ty Murray, Donny Osmond, Stacy Keibler, Sabrina Bryan, Marissa Jaret Winokur, and Giselle Fernandez.
Osbourne, who appeared on Season 9, was excited to come back to the show.
"This show changed my life completely. I owe so much to 'Dancing With the Stars.' I discovered myself through ballroom dancing of all things," said Osbourne. "To be able to come back... it's like one great big family. Once you're in, you're alumni, you're here forever and you feel the love, you feel the support. And you have so much compassion for the celebrities that are dancing out there and the pros. "
Reality star Audrina Patridge was the latest to be eliminated last week.
You can watch the show on ABC7 starting at 8 p.m.