She was a student in the first coeducational class at Phillips Exeter Academy, and wrote regularly for Seventeen magazine. She entered Yale University in 1971 and sent a collection of her writings to the editors of the New York Times Magazine. The asked her to write an article for them, which was published as An Eighteen Year Old Looks Back On Life on April 23, 1972. The article garnered a great deal of attention, including a letter from J. D. Salinger, then 53 years old, who complimented her writing and warned her of the dangers of publicity. They continued to correspond, and after finishing her freshman year, Maynard visited Salinger in New Hampshire. She dropped out of Yale and lived with Salinger for ten months. She published her first book, Looking Back, at the age of nineteen.
For many years, Maynard chose not to discuss her affair with Salinger in any of her writings, but broke her silence in a memoire called At Home In The World. She outraged many of Salinger's fans by selling his letters to her, saying was forced to do for financial reasons: she would have preferred to donate them to Beinecke Library.
Maynard gained widespread commercial acceptance with the publication of her novel "To Die For", about the Pamela Smart murder which was later produced as a film staring Nicole Kidman.