Harkness was willing to lend his assistance. After the construction of the Houston Field House was completed in late 1949, the team began play under Harkness in January 1950. After leading the team to a 4–6–0 record in its first year, Harkness helped form the Tri-State League, which would become the first attempt at league organization of college hockey in the east. Later that year, Harkness devised the RPI Holiday Tournament, which has taken place every year since 1951, making it the oldest in-season tournament in the nation. Harkness coached both hockey and lacrosse at Rensselaer throughout most of the 1950s and continued coaching hockey into the 1960s. That same year, Harkness led the hockey team to its first Tri-State title with a 15–3 overall record, though the title was later revoked when the team was found to be using an ineligible player. The team continued to improve rapidly on the ice under Harkness' guidance. In 1953, the team won its first official Tri-State championship and was invited to the NCAA Tournament for the first time, winning third place. The next season, Harkness guided RPI to an 18–5 overall record, a second straight Tri-State title, and a second straight trip to Colorado Springs for the NCAA Tournament. Though heavy underdogs, Harkness and his team upset traditional powerhouses Michigan and Minnesota to win the 1954 NCAA Championship. Harkness was the head coach of the men's ice hockey team at Rensselaer beginning with the 1949–1950 season through the 1962–1963 season. He led the team to a record of 176–96–7 and NCAA tournament appearances in 1953, 1954, and 1961, winning the NCAA title in 1954. His 1951–52 team averaged 8.28 goals per game, an NCAA record which stands today. He would leave the lacrosse team in 1958 to focus on RPI hockey after leading the team to a record of 112–26–2 in 14 years, and left RPI hockey in 1963 after three NCAA appearances, two Tri-State titles, one NCAA championship, and a record of 176–96–7 over 14 years. Moving to Ithaca In 1963, Harkness moved to Cornell University, where he replaced Paul Patten as the head coach of the hockey team. In his first year at Cornell, Harkness helped the team to a 12–10–1 record in the fledgling ECAC league. His second season saw the team record improve to 19 wins. His stature rose to legendary status with the recruitment of Ken Dryden.