In 1959 the Langners turned over operation of Westport Country Playhouse to other producers, among them James B. McKenzie. He held the title of Executive Producer for many of his 41 years with the Playhouse, and retired in 2000.

During his rich and varied theatrical career, McKenzie was at the helm of over 2000 productions, 419 of them at the Westport Country Playhouse. In addition to Westport, he was producer at 10 other regional theatres, including the American Conservatory Theatre in San Francisco and, in his native Wisconsin, the Peninsula Players. He also produced over 60 national and international tours, and four Broadway plays, receiving a Tony Award for And Miss Reardon Drinks a Little.

In the 1960s, McKenzie became the originator of a new business called star packages, rehearsing ten complete plays in New York every June, and sending them to ten different summer theatres, playing a week in each. More than 52 summer theatres, including Westport, shared the nationwide circuit.

In 1985, the Playhouse's future was threatened by the possibility of a shopping center taking over the property. McKenzie led 27 ardent theatre supporters in a successful drive to purchase the Playhouse and its land, thus insuring its future.

Throughout the McKenzie decades Westport Country Playhouse continued to present new works, recent Broadway successes, classics, and some of the country's top actors. Such plays as Leonard Gershe's Butterflies Are Free, the musical King of Hearts, Alan Ayckbourn's Absurd Person Singular, and An Almost Perfect Person with Colleen Dewhurst transferred to Broadway soon after their Playhouse premieres.

Some of the stars of this period included Alan Alda, Cicely Tyson, Geraldine Page, Van Johnson, Charles Durning, Richard Thomas, Jane Powell, Sandy Dennis, Eileen Heckart, Robert Morse, and Stiller and Meara. Many newcomers made early appearances at the Playhouse during this period, perhaps the most celebrated discovery being a gawky teenager who earned her Equity card and received a standing ovation on opening night for her performance as The Girl in The Fantasticks. Her name was Liza Minnelli.

In recognition of his theatrical producing endeavors, McKenzie received the Conservator of American Arts Award, the Connecticut Critics Circle Award for Outstanding Contribution to Theatre in 1993, a Lifetime Achievement Award by the Town of Westport in 1998, and an honor dear to his heart, the St. Mary Alumni Achievement Award.

Looking back on his career that spanned over half a century, McKenzie said, "The theatre is always dying, and the theatre is always renewing itself. The theatre is always disastrous, and the theatre is always wonderful..."