2009-10: Zach Stepan skated for the U16 team at Shattuck-St. Mary's School in Faribeault, Minnesota. Missing some time due to illness, he played 40 games and scored 19 goals with 23 assists and 20 penalty minutes. Stepan participated in USA Hockey's National Team Development Program camp and was selected by Waterloo in the first round (10th overall) of the 2010 USHL Futures Draft.
2010-11: Stepan began the year competing for the USA in the Select 17 Five Nations Cup in Switzerland and played for Shattuck in the pre-season Minnesota Elite High School League and Bauer NIT tournaments. In the regular season, he was the second-leading scorer for Shattuck's Tier 1 U18 national championship team. Stepan scored 1 goal with 4 assists and was plus-five with 2 penalty minutes in four games for the USA in Switzerland. He scored 6 goals with 10 assists and had 6 penalty minutes in 15 elite league games. In three NIT games he scored 2 goals with 5 assists. Stepan skated in all 54 games for Shattuck-St. Mary's and had 25 goals with 39 assists and 20 penalty minutes. Shattuck defeated the Mid-Fairfield Blues in the national championship game to finish 45-6-3. Stepan committed to playing college hockey at Ohio State in 2013-14.
2011-12: Stepan competed for Shattuck-St. Mary's in the Upper Midwest High School Elite League in the fall and skated in 50 games for Shattuck in his senior season. The Sabres won the U18 Tier 1 National Championship for the second straight season. Stepan scored 7 goals with 13 assists and had 6 penalty minutes in 15 games during the Elite League season. During the regular season he scored 22 goals with 43 assists and had 20 penalty minutes. Shattuck defeated the LA Junior Kings, 2-1, in the national championship game to finish 50-5-2. Stepan was invited to the NHL Draft Combine and ranked 53rd amongst North American skaters in Central Scouting's final rankings prior to the 2012 NHL Draft.
2012-13: Stepan was the third-leading scorer for Waterloo in the USHL and won a goal medal with the USA squad at the 2012 World Junior A Challenge. He scored 32 goals with 46 assists in 56 games and was +25 with 50 minutes. The Black Hawks finished third in the West Conference and lost to second-place Fargo in overtime of the decisive fifth game of their playoff series. Stepan scored 3 goals with 1 assist and was -1 in the playoffs. He scored 2 goals with 2 assists and had 2 penalty minutes in four games at the WJAC. In May 2013 he announced that he would play college hockey at Minnesota State and not Ohio State – which had fired head coach Mark Osiecki.
Stepan is a modestly-sized forward who plays bigger than would be expected of a player his size. He has some speed and skill, and can maneuver to open spaces on the ice to create some offensive opportunities. He is not as skilled a player as his cousin Derek, so he makes up for that shortcoming by working hard. At this stage, Stepan looks like a player that could eventually spend time on the second or third line, depending on how his offensive game progresses.
After a stellar high school career and a solid year of transition in the USHL with Waterloo, Stepan will play at the Minnesota State University-Mankato for at least two to three years. He can use this time to mature physically and improve his offensive skills. He has solid top-six potential.