Martin grew up in Princeton, New Jersey. Her mother was a preschool teacher, and her father was a cartoonist for the New Yorker. After high school Martin attended Smith College, where she majored in early-childhood education and child psychology. After college she worked with special needs children in schools. She then decided to go into publishing, working for Pocket Books and Scholastic, before becoming a writer herself, something she had always had an interest in. In 1983 she published her first children's book, Bummer Summer, and in 1985 the first book in the Babysitters Club was released. Martin wrote 35 books in the series, which now includes over 130 books, not including the spin-offs.
Martin has also written many single novels, many of which are set in the 1960s. One of those novels,
A Corner Of the Universe, won a Newbery Honor in 2003.
