Cecelia DeMarco played both basketball and lacrosse for four seasons at BSC. She led both teams in scoring as a junior and senior while leading the women's basketball team to three state championships. Cecelia was president of the Physical Education Major's Club and was Director of the Student Union Board of Governors her senior year. Basketball was her love both as a player and soon to be coach.

Following her graduation in 1973, Cecelia went on to be the head coach at Bishop Fenwick High School (1973-76). She joined the college ranks in 1976-77 as an assistant coach at Washington State where she earned her masters in sports psychology. She then returned to New England to become head coach at the University of New Hampshire for the next nine seasons. There she compiled a 135-86 record earning Converse district I "Coach of the Year" honors in 1983 after a 24-7 season. In 1997, Cecelia was inducted into the University of New Hampshire's Hall of Fame.

She left UNH in 1987 to return to Bridgewater State as the director of athletics until 1990. Then in 1990 she returned to the coaching ranks at Yale where she went on to become Yale's all-time winningingest coach from 1990-1999.

DeMarco returned to coaching in 2007 and took the helm of the MIT Engineers where she led the team to a 12-win season, their highest total in over ten seasons. The team qualified for the NEWMAC Tournament for just the second time in program history.

From 2009-2010, DeMarco served as an assistant coach for the University of Massachusetts-Amherst.  She then became the head coach at Endicott College prior to the 2010-2011 season.