In the 1940s John C. Wilson, whom Noel Coward described as "a man with his head in the clouds and his feet planted squarely in the box office" joined the Langners in the Playhouse management. Wilson's proté, Martin Manulis, soon became the Managing Director and instituted the apprentice system, a training program for young aspiring theatre professionals that continues to this day. Many past Westport Country Playhouse apprentices have gone on to great success in theatre and other ventures, including composer/lyricist Stephen Sondheim, screenwriter Frank Perry, television host Sally Jesse Raphael, composer Mary Rodgers, actor Carey Elwes, and actress Tammy Grimes, who "graduated" from the apprentice program and became the $20 a week hostess at the restaurant adjacent to the Playhouse the next summer.

Throughout the 1940s and 1950s, except for four seasons during WWII when gasoline rationing prevented audiences from getting to the theatre and there were no productions, the Playhouse continued to produce acclaimed productions of plays featuring major stars. Notable successes included the world premieres of William Inge's Come Back, Little Sheba, starring Shirley Booth, and Horton Foote's The Trip to Bountiful, both of which transferred to Broadway.

In a 1999 interview with Pat Grandjean of Connecticut magazine, Philip Langner, who had also joined his parents in the management of the Playhouse, recalled some of the highlights and challenges of producing summer theatre during that period:

Whenever a summer thunderstorm rolled in, the dialogue onstage became inaudible. "At times, you'd have to suspend the show for 10 minutes while the rain subsided," recalls Philip Langner. "Often, the electricity would go off. Then we'd use headlights we had stored in the rafters, running them off a car battery. Once we drove a bunch of cars up to the windows and shined their headlights into the auditorium."

Tallulah Bankhead recreated her stage success in Her Cardboard Lover at the Playhouse in 1941:

"She was totally crazy, mind-bogglingly so," recalls Philip Langner. During Lover's run she was surrogate mom to a lion cub she had spirited away from a circus troupe in Nevada. Known to use Lawrence and Armina's bedroom at Langnerlane Farm as its den, Bankhead's constant companion also shared all of his mistress's curtain calls.

Tyrone Power was about to open in Liliom, directed by Lee Strasberg, at the Playhouse in 1941 when Darryl Zanuck, the powerful head of 20th Century Fox, demanded that he return to Hollywood promptly to re-shoot scenes from A Yank in the RAF, his upcoming film with Betty Grable:

"Tyrone wanted to stay," says Philip Langner. "In those days movie companies had great power. They owned the actors. So he couldn't refuse to go to Hollywood without getting into big trouble." But Lawrence Langner found a trump card to play. The theater's formidable Bridgeport-based attorney Kenneth Bradley invoked a 300-year-old Connecticut Blue Law under which one could keep a man from leaving the state if he tried to do so before fulfilling a contract. A local sheriff came to the Playhouse to confront a delighted Power, who was forced to phone Fox to explain his new dilemma.