Mike Berenstain's earliest work in the U.S. Library of Congress catalog was published in 1976: K'tonton on an Island in the Sea by Sadie Rose Weilerstein, which he illustrated as Michael Berenstain (Philadelphia: Jewish Publication Society of America). The third K'tonton book, it features "Adventures of a thumb-sized Jewish boy who must fend for himself when stranded on an island." During the next three years he wrote and illustrated four instructive picture books published by David McKay, The Castle Book and sequels on ships, armor, and lighthouses. He first collaborated with his parents by illustrating two picture books, The Day of the Dinosaur and After the Dinosaurs (Random House, 1987 and 1988), after which he did several dinosaur books himself. He is credited as a creator of his family's bear family beginning in 1995 as illustrator of the Bear Scouts subseries. Mike continued the Berenstain Bears with his mother following Stan's death in 2005, and took over creation of the series after Jan's death in 2012. His older brother Leo Berenstain is involved in management of the franchise.