Patricia Clapp was born in 1912 in Boston. She attended the Columbia University School of Journalism. She describes herself as a "theater person" and has worked with community theater for more than forty years. Clapp has directed and written numerous plays for children, young adults, and adults; and she has had several poems published. Clapp is a grandmother and great-grandmother who lives in Upper Montclair, New Jersey.
Events in her life are reflected in her works for young adults. After receiving a genealogy of her family, the author discovered that an ancestor, Constance Hopkins, came over on the Mayflower. Intending to write a play about her life, Clapp decided instead to write her story as a diary or journal. The result was Constance: A Story of Early Plymouth, a novel for young adults. After reading issues of Century magazine, Clapp's interest was sparked by articles about the Civil War—including excerpts from a diary of a young woman. This prompted her to begin writing what would become The Tamarack Tree.

Constance: A Story of Early Plymouth was a runner-up for the 1969 National Book Award for Children's Literature and the 1969 Lewis Carroll Shelf Award. Witches' Children was selected as an ALA Best Book for Young Adults. The Tamarack Tree also received strong reviews in Horn Book and School Library Journal. The Horn Book review states, "Clapp lets the character speak for herself," and the descriptions of life in Vicksburg "create an unforgettable background." All three novels are still in print.

Even though Clapp's titles are ten to thirty years old, they remain popular with students and teachers. Frequently, her works are used to teach social studies and appear on library recommended reading lists. In some classrooms, her works are used to supplement traditional history texts in order to engage student interest in American history. Her ability to give her characters a voice reaches each generation of new readers.