Stephanie Calmenson was working as a teacher when she decided to make a counting book, a book that would feature monkeys and would focus on addition and subtraction. One Little Monkey was her first book in the early 1980s and it was published by Parent Magazine Press t this point in her life, Calmenson was struggling with her finances and made a move into publishing. Her first children's book position was at Doubleday as an editor while she worked on her Master's Degree. Joanna Cole, author of the Magic School Bus stories was also working as an editor and needed an assistant. Calmenson got the job and Cole became Calmenson's mentor. Eventually they did several books together. As Calmenson grew in her abilities, she left to take on the editorship of Humpty Dumpty. After a few months it folded and she was laid off. She went freelance but returned when there was an opening at Doubleday. Eventually, Calmenson left again and became Director of the Book Club at Parent Magazine as well as a full time writer in her own right. She has written over a hundred books.