Shelley joined the cast of Charlie's Angels in late-May of 1979. After a long search for a new girl to fill-in the slot left open by original Angel Kate Jackson, Shelley was finally cast as Charlie's newest Angel Tiffany Welles. Shelley was already a Supermodel by then and was famous for being THE Charlie Perfume Girl from those glamorous and fabulous Revlon Charlie commercials and print ads. Her Supermodel status had brought her to the attention of Hollywood, which was more than willing to take the Supermodel into greater heights of fame and fortune. Nolan Miller, the wardrobe designer on the series said, "Shelley came to the studio and everyone in wardrobe fell in love with her and I begged Aaron (Spelling), please hire her; She's so chic and she's so great." Ed Lakso, a writer/producer on the show, said, "Believe it or not, the headline 'Charlie Girl becomes the new Charlie's Angel' carried a lot of weight." Executive producer Aaron Spelling told TV Guide, "We decided she was a nice person with sparkle and intelligence." When Shelley's debut episode "Love Boat Angels" was aired, it topped the Nielsen ratings.
