Recruited from Stoneham High School, Gagne became a starter midway through her freshman season. Installed as a full-time starter at left wing as a sophomore, she asserted herself as a scoring threat, including a three goal and three assist outing against Rhode Island. Gagne was chosen All-Patriot League for her efforts in helping the team finish 8-9-1. In her junior season, Holy Cross notched its first ever winning campaign, finishing 12-7-1, and qualified for the ECAC Tournament, thanks in part to hear team-leading 12 goals. The team finished 12-7-1 again her senior season in 1994, earning a berth to the Patriot League Tournament. She finished the season as team leader with 19 goals and earned honors as First Team All-Patriot League, Patriot League Offensive Player of the Year, and Northeast Regional All-American. She was also the first Holy Cross player chosen as a North-South All Star. Gagne led the Patriot League in scoring three consecutive seasons (1992-1994), graduated with a school record 48 goals, and was named to the Patriot League All-Decade Team for the 1990s.