Francine Pascal—a former soap-opera writer and creator of the extremely successful Sweet Valley High book series—died on Sunday in Manhattan’s NewYork-Presbyterian Hospital. Her daughter, Laurie Wenk-Pascal, confirmed to The New York Times that her mother’s death was due to lymphoma. She was 92.Selling “well over 200 million copies,” Sweet Valley High introduced the Valley Girl aesthetic to the rest of the country and “millions of teenagers that no one in publishing knew existed” to the industry, according to a 1986 interview Pascal gave to the Los Angeles Times (via NYT). Beginning with a novel called Double Love in 1983, Pascal’s young adult series followed two identical twins named Elizabeth and Jessica Wakefield, as they explored the worlds of boys, friendship, and cheerleading at their Southern California high school. Pascal wrote the first 12 books in the series herself, then handed the reins and a number of extremely detailed outlines to a group of ghostwriters, who went on to publish 181 novels in the primary series, as well as multiple spinoff series like Sweet Valley Kids and Sweet Valley University, which followed the twins at various stages in their lives. The series officially concluded in 2003, but Pascal followed it up with two novels checking in on the twins as adults—titled Sweet Valley Confidential and The Sweet Life—published in 2011 and 2012 respectively. The series also inspired a popular television spinoff of the same name, that starred real-life twins Brittany and Cynthia Daniel and ran for 88 episodes from 1994 through 1997.“When I first thought of the idea for Sweet Valley High, I loved the idea of high school as microcosm of the real world. And what I really liked was how it moved things on from Sleeping Beauty-esque romance novels where the girl had to wait for the hero,” Pascal told The Guardian in 2012. “This would be girl-driven, very different, I decided—and indeed it is… I think that was of great appeal to readers. There wasn't anything like that around."Pascal was born in 1932 in Manhattan and grew up in Queens, New York. In addition to Sweet Valley High, she also wrote for a number of magazines including Cosmopolitan and Ladies’ Home Journal early in her career, as well as 1964 soap opera The Young Marrieds. She also wrote several other novels including her first, Hangin’ Out With Cici (1977), which was later turned into an ABC afterschool special. Pascal is survived by two of her three daughters, six grandchildren and five great-grandchildren.