Happy 63rd birthday, Twiggy.
LIFE.com celebrates her career and her enduring style with a series of rare pictures — shot in California for a feature that never appeared in the magazine — by long-time LIFE photographer Ralph Crane. Captured at the very height of her fame as one of the first-ever supermodels, and during her first visit to the U.S. when she was all of 18 years old, the Twiggy in most of these pictures seems remarkably cool and sophisticated for one so young. (Perhaps not surprising, considering that she’d been one of the most famous figures — and had one of the most famous figures — in the world for the previous whirlwind year.)
See the photos here on LIFE.com