Ann Matthews Martin is an American children's fiction writer, best known for The Baby-sitters Club series.

Born and raised in Princeton, New Jersey, she grew up with her parents and her younger sister, Jane. Ann graduated from Smith College in 1978 with a double major in psychology and elementary education.

She began her career as a teacher and then became an editor of children's books. Her first published book was Bummer Summer in 1983.

In 1990, she founded the Ann M. Martin Foundation, which provides grants to causes benefiting children, education and literacy programs, and homeless people and animals. Ann currently resides in Hudson Valley, New York.