"Theatre Building Chicago has been my home since 1985," she said in a statement. "During my tenure, the company increased the use of its three-theatre complex from 82 percent to 98 percent, went from the occasional musical presentation to a full season of 20-plus new musicals in development, doubled the size of the staff, and re-focused and emphasized the public profile of the company. The board wants to take TBC in a new direction while I look forward to more artistic and programmatic endeavors."

Mazzonelli has helmed TBC since 1997, stepping in for Ruth Higgins, who co-founded the company with the late Byron Schaffer, Jr.

"Change is the one constant here at TBC," stated board president Craig Wilson. "TBC will continue in new and exciting directions. We thank Joan for her great contributions, wish her well and have left the door open to possible endeavors with us in the future."

He was more blunt in an interview with the Chicago Tribune, saying that the board was "committed to building a full subscription season" and "we didn't think that Joan was the person to take it to the next level in terms of getting corporate sponsorships and so on."

TBC's director of operations Thom Van Ermen will assume day-to-day operations while the board reviews candidates to serve as the new executive director. Mazzonelli was past president of Child's Play Touring Theatre, past vice president of the Chicago Dance and Music Alliance, past treasurer of the League of Chicago Theatres, past secretary of the Illinois Theatre Association, and past board member of the National Alliance for Musical Theatre. She was an adjunct faculty member at Columbia College Chicago. She has served on peer review panels for the Illinois Arts Council and for the City of Chicago's Department of Cultural Affairs. Previously in New York City she was executive director and co-founder of the Opera Shop at the Vineyard Theatre, managing director for On Stage Productions and tour director for the National Shakespeare Company. She has free-lanced as a stage director, costume designer and dramaturg, and she has sung with a diverse array of chorales and choruses. She is a member of the Dramatists Guild and currently serves on the artistic and technical team of the Joseph Jefferson Awards Committee.

Theatre Building Chicago is an incubator for developing theatre companies, new musicals and emerging theatre artists. TBC's Musical Development Program offers works in multiple stages of development and nurtures new works through its Musical Theatre Writers Workshop and through collaboration with theatre companies and artists across the country. TBC series include: STAGES, an annual festival of new musicals in progress Aug. 21-23, New Musicals for Kids and Monday Night Musicals (once-a-month concert readings).

There are three 150-seat venues in the complex, housing TBC projects and work of renting troupes.