Chris Cassidy played fullback and linebacker for Lincoln Pius X, helping the Thunderbolts to the state playoffs in 2015, 2016 and 2017. He was a Lincoln Journal Star second-team Super-State linebacker as a senior in 2017, when he made 71 tackles and also rushed for 858 yards and 10 touchdowns. He added an interception and was named first-team all-state by the Omaha World-Herald. As a junior, Cassidy ran for 342 yards and a touchdown while recording 300 total yards and six combined touchdowns as a sophomore. Cassidy made 47 tackles in 2016, and 36 stops in 2015. Cassidy was an honorable-mention all-state selection in 2016 by the Omaha World-Herald.