Cassidy was born and raised in and around Chicago. A graduate of Millikin's BFA Acting program, she had the opportunity to study abroad in London where she was honored to work at Shakespeare's Globe Theatre and with Punchdrunk. She was also an instructor in the first year of Illinois Shakespeare Festival's educational program. Since graduating, she has worked with Chicago Shakespeare, Notre Dame Shakespeare, Adventure Stage, Metropolis Performing Arts, First Folio, Signal Ensemble, Lifeline, and others. Her television work includes The Dreamers and extra work on The Dilemma. Along with acting, Cassidy sings and plays viola/violin. She traveled the world as an actor/musician with Once the Musical, performing original music and covers in benefit concerts across the country. While understudying her two roles, she performed in several cities including Tokyo, Boston, and the Kennedy Center in Washington, DC. She plays songwriting gigs in Chicago and joins band Youth in a Roman Field in New York.
