In 2015, the Mid Atlantic Prep Hockey League unanimously voted to name the MAPHL Coach Of The Year award the “Ervin J. Terwilliger Coach Of The Year Award”, an honor that is voted upon by all the head coaches in the league.

Terwilliger began coaching Mt. St. Joseph in 1991 and accumulated 248 wins, 5 state titles, and 10 MIAA championships. He was a major contributor to the development of high school hockey in the Baltimore-Washington area. He was a mentor to many coaches and players who grew up in the region, including current head coaches Rob Trantin (Spalding) and Mike Marley (Mt. St. Joseph). Terwilliger was uncompromising when it came to sportsmanship and adherence to his guiding principles. Erv's “team first” philosophy would be the hallmark of his coaching legacy, producing admiration from his players and rival coaches alike. Former long time Landon head coach, Hans Farnstrom, stated, “As a coach, Erv was always a gentleman and a true sportsman. I always found him classy, genuine, and interested in what was best not only for his team, but for high school hockey.”