Cassidy concentrated on stage acting for most of the 1980's and early 1990's. He appeared in Broadway and West End productions such as Mass Appeal, Bus Stop and Blood Brothers, with a half brother David for over a year on Broadway.
Shaun Cassidy grew up in Los Angeles and New York City in an Irish American family. Besides an older half brother, David Cassidy, he has two younger brothers, Patrick and Ryan Cassidy.
