Billie Letts, a teacher, activist, and bestselling author, died Saturday in Tulsa, Oklahoma. She was 76. The cause was acute myeloid leukemia. Her first novel, "Where the Heart Is", published when she was 57, reached number one on the New York Times paperback bestseller list and became a popular film, starring Natalie Portman and Ashley Judd. Born on May 30, 1938, in Tulsa, to Bill and Virginia Gipson, Ms. Letts graduated from Union High School in Tulsa, received a Bachelor of Science Degree in English and Education from Southeast Missouri State University, and earned a Master's Degree in Behavioral Studies from Southeastern Oklahoma State University. Her teaching career spanned thirty years, ranging from elementary school to the university level. An avid Democrat and activist who protested on behalf of the peace movement, both during the Vietnam and Iraq Wars, Ms. Letts, at the age of 69, was handcuffed and arrested while protesting an appearance by then-Vice President Dick Cheney in Tulsa. Success as a writer came relatively late for Ms. Letts. Though she practiced her craft for many years with unpublished poetry and unproduced screenplays, it was not until she expanded a short story -- about a pregnant unwed teenager who takes up residence in a Wal-Mart -- into the novel "Where the Heart Is" that her writing found an audience. It was published in fourteen countries with more than three million copies sold worldwide. The book became a selection of Oprah's Book Club in 1998. Ms. Letts was inducted into the Oklahoma Writers Hall of Fame that same year. Ms. Letts wrote three subsequent novels: "The Honk and Holler Opening Soon" in 1998, "Shoot the Moon" in 2004, and "Made in the U.S.A". in 2008. She married Dennis Letts on November 30, 1958. After teaching stints in a variety of locations, including Cape Girardeau, Missouri, and Champaign, Illinois, the Lettses settled in Durant, Oklahoma, where they taught English at Southeastern Oklahoma State University for thirty years. In addition to their teaching careers, they served as substitute parents for many lost souls, struggling artists, disaffected young people, and displaced students. One example: They taught -- and hosted and befriended -- a hundred and twenty-five Vietnamese refugees relocated to Durant in 1978. Ms. Letts retired from teaching two years after the success of her first book. Mr. Letts also had a productive second career, as an actor, after retiring from teaching. (He plays a small role in the film version of "Where the Heart Is".) They relocated to Tulsa in 2000. Mr. Letts preceded her in death in 2008. Surviving are three sons and their wives: Dana and Deborah Letts, Wagoner, OK; Shawn and Sharifah Letts, Singapore; and Tracy Letts and Carrie Coon, Chicago. A Memorial Service will be held at All Souls Unitarian Church in Tulsa, OK on Saturday, August 9, at 2:00 p.m. In lieu of flowers, donations can be made "In Memory of Billie Letts" online at www.tulsalibrarytrust.org, or checks can be made out to: Tulsa Library Trust 400 Civic Center Tulsa, OK 74103