Harriet Ziefert is a former elementary school teacher from New Jersey. A graduate of Smith College, she also holds an MA in education from NYU. She is the bestselling author of more than 250 children's books and has developed easy-to-read series for several major publishing houses. As founder of Blue Apple Books, she has published over 500 titles, many of which have become bestselling modern classics. Harriet Ziefert continues to create and publish books from her home in Great Barrington, Massachusetts. Mercè Galí is an illustrator from Barcelona. She grew up surrounded by stories in her parents' bookstore and studied illustration and fine arts at the University of Barcelona, specializing in engraving. She mainly illustrates children's books for a number of publishing houses in various countries.

Her books have been recognized at the Bologna Children's Book Fair and her project, Petit Indi, was a finalist in the Silent Book competition. Mercè Galí lives and works in Barcelona, Spain.