The article of clothing with which Katharine Hepburn is most closely associated is trousers. The actress’ fondness for pants—before they were considered ladylike—was not only a fashion statement but, to many, a symbol of stubborn independence and a declaration of modernity.
But many of Hepburn’s roles—and her legacy as a four-time Oscar-winning actress is certainly more notable than that as fashion trendsetter—required the woman LIFE called a “lanky, coltish thoroughbred” to adhere to more feminine standards.
For her 1939 Broadway turn in one of her most famous roles, socialite Tracy Lord in The Philadelphia Story, Hepburn hung up the pants and went all in on frilliness. LIFE described the process of designing her wardrobe:
To make the role of Tracy Lord both credible and sympathetic, it was essential; that Katharine Hepburn be made to look irresistibly seductive every minute she was on the stage. Valentina, who dresses Lynn Fontanne and Katharine Cornell, was called upon to make the clothes. Her creations, designed to give soft, feminine allure to tall, angular Miss Hepburn (whose favorite outfit in real life is a man’s suit of clothes) are shown on this and the following page.
Those creations featured silk-crepe and mousseline, flowing gowns and girdles. The extra effort, from wardrobe to performances, paid off. After a string of Hollywood flops earned her the unwanted label "box office poison," Hepburn acquired the rights to the play, sold them to MGM, starred in the 1940 movie adaptation and revived her onscreen career.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk.