A 2012 graduate of Westwood High School in Westwood, Mass., Brown was a four-year letter winner in lacrosse and field hockey. She also lettered in ice hockey. Westwood, one of the top lacrosse programs in Massachusetts won Tri-Valley League Championship titles in 2009, 2010, 2011 and 2012, South Sectional Championship titles in 2009, 2010, 2011 and 2012 and State Championship titles in 2009, 2011 and 2012. A captain in her senior season, Brown was a two-time Tri-Valley League All-Star, an ESPN Boston MIAA All-State Girls Lacrosse Team - Honorable Mention recipient, a Bay State Games Lacrosse Silver Medalist in 2010, a Bronze Medalist in 2009, and was awarded the Unsung Hero Award in 2012. She was coached by Leslie Frank.
Mollie Brooks Brown is the daughter of Edward and Lori Brown. She has two sisters (Annie and Abbie). Annie was a four-year defender for the Keene State women's lacrosse team and is currently the assistant coach at Wheaton College. Abbie was a goalie on the Fitchburg State University field hockey team.