Jean Cassels began her work as an illustrator in 1969 with biology textbooks. Since then she has illustrated encyclopedias, literature, poetry, monthly magazines and dictionaries for children. She has over 60 titles for young people, including:
- Two Bobbies ... a Dog & a Cat: A True Story of Katrina, Friendship, and Survival (August, 2008) - Winner of 23 Awards 2009-2013
- Br'er Rabbit Captured! (The sequel to The Mysterious Collection of David Harleyson)
- Armies of Ants, Fabulous Frogs, Chameleons, Creepy Beetles, and Butterflies (Scholastic Books)
- Groundhog Stays Up Late (Walker & Co.)
- Swift as the Wind - the Cheetah, (Orchard Books)
- Earthmates - poetry ( Marshall Cavendish)
- Once I Knew a Spider (Walker & Co.)
- Lonesome George, the Giant Tortoise (Walker & Co.) - 2004 winner of the Giverny Book Award for Best Science Children's Book.
- The Mysterious Collection of Dr. David Harleyson (Walker & Co.) - 2004 winner of the Golden Kite Award.
Her work was juried into the New York Society of Illustrators show, "The Original Art - 1997;" "Illustrators 40" 1998; and "The Original Art - 2004." Her training was at The School of The Art Institute, Chicago; The University of Illinois, Chicago; and with Auseklis Ozols at the New Orleans Academy of Fine Arts. A teacher of drawing, figure drawing, and painting with gouache, she has been on the NOAFA faculty since 1994.