The Millbrook Playhouse is a unique barn theatre, having operated as a professional summer stock theatre since 1963. The theatrical companies hired each summer continue to possess highly diverse skills and techniques and provide varied entertainment. Hundreds of plays have been performed, entertaining approximately 1,000 people per week.

Millbrook has provided a stage for many aspiring teachers, theatre managers, producers, actors and actresses. The Shubert Theatre and Circle in the Square on Broadway, The Actor's Theatre of Louisville, The Timberlake Theatre in Illinois, the movie "Dune", and the television series "L.A. Law" and "Twin Peaks", various daytime television serials, TV commercials, industrial films, television specials, and various universities have all included former Millbrook performers and staff members. Two of the most notable are Kyle MacLachlan, star of "Twin Peaks" and "Dune", and Michael Tucker of "L.A. Law" fame.

Governed by a non-profit corporation with a volunteer board of directors, Millbrook continues to grow and develop. In 1977, the Cabaret Theatre was added as an alternative to the Main Stage Productions, providing entertainment for more mature audiences. In 1991, efforts began to purchase the barn and surrounding property which for so many years was leased from the estates of the late Joseph W. Bechdel and Louis S. Winner families. The purchase of the barn will no doubt yield even more growth potential.

The name, Millbrook, was associated with this barn long before the Playhouse was established. However, the spelling was slightly different as evidenced by the name, Millbruek, attached to the courtyard mailbox. This name was given to the farm by former owners, Mr. and Mrs. Sedgewick Kistler, who purchased the property in 1915. The original barn, the portion which now houses the main stage and seating, was enlarged to accommodate the Kistler's sizable herd of registered Holstein cattle.

Prior to the Kistler's ownership, the Millbrook barn was owned by the Sanderson family for nearly three-quarters of a century. In addition to farming the Sandersons operated a grist mill which stood north of the barn, where the present Clinton Country Club is now located. This grist mill and its mill stream, a portion of which is still recognizable on the golf course property along Country Club Lane, have been remembered through time and today "Millbrook" is an 'enjoyable community asset.