Kass officially moved to Paris at the age of 18. Soon after, she received exposure on the cover of magazines worldwide, such as Vogue (France) in 1997, ELLE (Australia), Image (UK), Madame Figaro, Numero France, Vogue (France), and Vogue (US) in 1999. In 1999, Kass modeled for top designers such as Marc Jacobs, Michael Kors, Calvin Klein, Ralph Lauren, Donna Karan, Dolce & Gabbana, Gucci, Prada, Versace, Fendi, Chanel, Chloe, Valentino, Louis Vuitton, and Givenchy. In addition, Kass has posed in numerous advertisements for Calvin Klein, Chanel, Donna Karan, Givenchy, Fendi, Michael Kors, Versace, and also for General Motors. She is also recognized for her appearances in a The Gap denim advertising campaign. Kass was a spokesperson for Sephora, one of the world's leading cosmetics retailers, and theChristian Dior perfume, J'adore. Kass was awarded by Vogue as "Model of the Year" at the 2000 VH1/Vogue Fashion Awards.