The June 20 festivities will kick off at 12:30 PM and will feature a sing-along led by cast members of the Stephen Schwartz musical. Wicked fans will be able to join the show's current Elphaba, Kristy Cates, in a sing-along version of the show's anthem, "Defying Gravity."

Attendees are also invited to attend the celebration dressed as Elphaba, the not-so-Wicked Witch of the West. The first 365 witches — Wickedly dressed and fully greenified — will be given a pair of tickets to a future Wicked performance.

The open-ended Chicago production of Wicked began performances at the Ford Center for the Performing Arts' Oriental Theatre June 24, 2005, and officially opened July 13. The original Chicago company included Ana Gasteyer and Kate Reinders as, respectively, the green-faced and curly-locked witches.

Based on Gregory Maguire's novel, which turned every Oz myth inside out, Wicked explores the early life of the witches of Oz: Glinda and Elphaba. The two main characters meet at Shiz, a school where both hope to take up sorcery. Glinda is madly popular and Elphaba is, well, green. By a misunderstanding, they wind up roommates and, after an initial period of mutual loathing, begin to learn something about each other. Their life paths continue to intersect through a shared love, entry into the Emerald City and interaction with the Wizard himself. Eventually, their choices and convictions take them on widely different paths.

The Water Tower Square Park is located at the corner of Michigan and Pearson. Chicago's Ford Center for the Performing Arts/Oriental Theatre is located at 24 West Randolph Street. Tickets for Wicked are available at all Broadway in Chicago box offices (22 W. Monroe Street, 24 W. Randolph Street and 151 West Randolph Street) or by calling (312) 902-1400.

For more information about Wicked visit www.wickedthemusical.com.