2010-11: J.T. Compher played for Team Illinois U16 and skated for the Glenbrook North High School team. In 34 games for Team Illinois he scored 17 goals with 22 assists and had 56 penalty minutes. Compher committed to playing college hockey at the University of Michigan in 2013-14.
2011-12: Compher joined the USA National Team Development Program (NTDP) in Ann Arbor Michigan, skating with the U17 team during the season and in three international events and playing for the USA in the 2012 U18 World Junior Championship. Compher scored 2 goals with 3 assists and was plus-seven in six games as the USA captured the gold medal at the WJC. In 18 regular season games with the NDTP U18 team Compher scored 8 goals with 5 assists. The NTDP U17 team had a successful season, winning the 2012 U18 Vlad Dzurilla Tournament, finishing second in the 2012 U17 World Hockey Challenge and capturing the Four Nations Tournament in Russia in November. Compher was the team's second leading scorer – tallying 15 goals with a team-high 27 assists in 40 games.
2012-13: Compher skated with the USA NTDP U18 squad and represented the USA in the 2013 World Junior Championship tournament. Compher was the U18 team's second-leading scorer, finishing with 18 goals and 31 assists in 55 games and was plus-12 with 53 penalty minutes. Compher was the second leading scorer for the silver medal-winning USA squad at the U 18 WJC, trailing only Tyler Motte, scoring 3 goals with 4 assists and finishing plus-two with 8 penalty minutes in seven games. In a thrilling gold medal game, the USA fell to Canada, 3-2. Compher was ranked 34th amongst North American skaters in Central Scouting's final rankings prior to the 2013 NHL Draft.