Cassidy grew up in Fairfax Station, VA where she started playing lacrosse in 3rd grade. After making the varsity team all four years in high school, she was made captain her senior year. After tearing her ACL senior year, her love for the sport drove her to attend all practices and help where she could giving her a taste for coaching.
In 2014 she decided to coach at her old high school, South County, first as assistant JV coach then in 2015 as head JV coach and lead that team to an undefeated season. She took a break from coaching to receive her bachelors degree while playing on various club teams. Cassidy now works at the National Museum of African American History & Culture as an Educator and is entering her 3rd year of coaching for Next Level.