In 1977, while working as a student teacher at a high school in Mountain View, California, Cassidy began his career as a juggling pedagogue by handing out 75 tennis balls to his sophomore remedial-reading class, along with instructions on juggling.
[2] Pleased with his students' response, Cassidy, along with his college friends Lorentzen and Rimbeaux, wrote and published Juggling for the Complete Klutz.
That same year Cassidy, Lorentzen, and Rimbeaux co-founded Klutz Press in Palo Alto, California.
[3] Juggling for the Complete Klutz, the company's most popular title, has sold over 2.5 million copies.
[5] In 2018, Cassidy became a board member of the nonprofit rafting company, ARTA River Trips.