Barbara, the daughter of Brooke and Doris Tidswell, grew up in New Jersey. She attended Rider College, but completed her bachelor of science in secondary education at the University of Alabama. She set aside a teaching career after an unpleasant stint as a student teacher. While living in Tuscaloosa she met her husband, Richard Park. They married in 1969 and moved to Scottsdale, Arizona where they raised two sons, Steven and David.
Park turned to writing in 1992. She is best known for her popular series of children's books featuring Junie B. Jones. She has also authored picture books for younger children and middle-grade novels for young readers. She won seven Children's Choice Awards and four Parents' Choice Awards.
Park died in November 2013 of ovarian cancer. Before her death she co-founded the charity Sisters in Survival to support others with the disease.