While attending Indiana University of Pennsylvania, McAdoo began working as an assistant high school coach in his sophomore year of college. He returned to his alma mater Homer-Center to be an assistant coach for the 1996 and 1997 seasons, then he was an assistant at Indiana Area High School from 1998 to 1999. McAdoo graduated from IUP summa cum laude in health and physical education. He then became a graduate assistant for the Michigan State Spartans football team under head coach Bobby Williams while pursuing a master's degree in kinesiology at Michigan State University. In the 2001 season, McAdoo earned his first collegiate coaching position as a graduate assistant for special teams and offense. McAdoo was the offensive line and tight ends coach at Fairfield University for the 2002 season, in what would be the final season for the Fairfield Stags football team. In 2003, McAdoo became a graduate assistant at the University of Pittsburgh under head coach Walt Harris and helped the team in the 2003 Continental Tire Bowl. After initially accepting an assistant coach position at Akron, McAdoo resigned to become offensive quality control coach for the New Orleans Saints in 2004 under head coach Jim Haslett. McAdoo interviewed with offensive coordinator Mike McCarthy. McAdoo coached tight ends and offensive tackles at Stanford for the 2005 spring camp, then resigned to be assistant offensive line and quality control coach for the San Francisco 49ers, reuniting with Mike McCarthy. In 2006, McCarthy became head coach for the Green Bay Packers and added McAdoo to his staff as tight ends coach. McAdoo coached tight ends for the Packers until the 2011 season, and then coached quarterbacks from 2012 to 2013. McAdoo was a member of the coaching staff of the 2010 Packers team that won Super Bowl XLV.
In 2014, McAdoo joined Tom Coughlin’s staff as the offensive coordinator for the New York Giants. In his first season as offensive coordinator, the Giants offense improved from the 28th-highest-scoring offense in 2013 under Kevin Gilbride to 13th in 2014. In 2015, the offense took another leap forward, becoming the sixth-highest-scoring offense despite losing starting left tackle Will Beatty, starting wide receiver Victor Cruz, and starting tight end Larry Donnell for most of the season due to injury.
Head coach (2016–2017)
On January 14, 2016, McAdoo was named the Giants’ 17th head coach in franchise history. On September 11, 2016, McAdoo won his first game as head coach when the Giants defeated the Dallas Cowboys 20–19. The Giants finished the 2016 season with an 11–5 record under McAdoo, tying the franchise record held by Dan Reeves for most regular season wins by a first year head coach. The Giants returned to the playoffs for the first time since 2011, but lost to the Green Bay Packers 38–13. The Giants' 2017 season was marred by numerous player injuries and other known controversies, which included some players being suspended for team violations, slumping the Giants to an 0–5 start, the first for the team since 2013 before getting a road victory in Week 6 against the Denver Broncos. On November 28, 2017 McAdoo replaced Eli Manning with Geno Smith prior to the Week 13 game against the Oakland Raiders, which ended Manning's 210-consecutive start streak. After losing 24–17 to the Oakland Raiders and sitting at 2–10, McAdoo was fired by the Giants on December 4, 2017, along with general manager Jerry Reese.
Jacksonville Jaguars
On February 11, 2020, McAdoo was hired by the Jacksonville Jaguars as their quarterbacks coach.
Personal life
McAdoo is married to his wife Toni, a fellow native of Homer City. They have a daughter and a son.
