"BOHEMIAN." The word comes up when discussing the French designer Isabel Marant. She grudgingly accepts the inescapable. "I hate to be put in a box," she says. "It's difficult to accept, but it's not a bad tag. I'm bohemian in spirit."

Although it accurately describes Marant's iconoclastic, freewheeling approach to life, as well as many of her enormously popular creations, from lace minidresses to fringe boots, it minimizes the scope of Marant's designs and her puritanical work ethic. Her attitude...