Cat Deeley steps back into her role as host as this Emmy-winning dance competition returns for Season 17 after an extended hiatus. Stephen "tWitch" Boss, a former contestant and occasional judge in past seasons, is part of the new regular judging panel, alongside musical theater star Matthew Morrison ("Glee") and dancer JoJo Siwa, who recently competed on "Dancing With the Stars." This new edition once again features dancers between the ages of 18 and 30 who compete each week across a variety of dance styles.