Nothing really prepares you to be First Lady," Nancy Reagan admits. And yet as captured in a yearlong style exhibit opening Nov. 10 at the Ronald Reagan Presidential Library in Simi Valley, Calif., when it came to dressing the part, Reagan never needed much schooling. Relying on designers like Bill Blass, James Galanos and Carolina Herrera to help her go from making an antidrug speech in the afternoon to a black-tie state dinner that evening, Reagan "never made a single faux pas," says Oscar de la Renta. Maybe not, but at least one person wasn't thrilled about Reagan's growing wardrobe. "Ronnie had always teased me about how I should clean out my closet," says Reagan, 86, of her late husband, who died in 2004. "Now I'm glad I held on to my dresses for so long!" And not only so she could show more than 80 of them (including her 1952 wedding gown) to the public. "Going through my closets has been a walk down memory lane," Reagan says, "for which I will always be grateful."