Mary-Kate Olsen and her twin sister, Ashley, known for their casual, layered, bohemian style, will wear red carpet-ready couture gowns in an ad campaign for Badgley Mischka.

"Ashley and Mary-Kate have grown up to become America's young style icons. They have an amazing sense of fashion and individuality that intrigued us," the design duo of Mark Badgley and James Mischka said Wednesday in a statement. The Olsens attended Badgley Mischka's fall preview at New York Fashion Week. The designers said the 19-year-old actresses "reflect the younger, edgier and more sensual glamour that we have incorporated in our latest fall collection."

Print ads featuring the Olsens will appear in the April issues of Vogue, Elle, InStyle and Vanity Fair magazines. In addition to the print ads, the campaign will appear in stores and on the Internet.

Gilles Bensimon was the one who photographed the twins, Mary-Kate appearing as a brunette and Ashley as a blond, in the presidential suite of the St. Regis Hotel in Manhattan. "We have been fans of Mark and James for years and were honored when approached to appear in the campaign," Ashley said in a statement.

As for the collection she's to promote, Mary-Kate described the clothes in the fall collection as "glamorous, beautiful, colorful and fun." Although last month, Mary-Kate was targeted by acid-tongued fashion critic Mr. Blackwell in his 46th annual "Worst Dressed" list and her clothes were called "bag lady rags" and "depressingly decayed," Badgley Mischka seems to appreciate the young star.