Northern Arizona Lumberjacks cross country

Northern Arizona Lumberjacks cross country are the cross country teams of Northern Arizona University in Flagstaff, Arizona. The Lumberjacks compete in the Big Sky Conference at the Division I level in the NCAA and are head coached by Mike Smith.

The men's team have won 6 national championships and were runner up 5 times, and the women's team were the national runner up 1 time. Many of the team's runners compete in the Olympic Games, with alumni representing a total of 11 nations since the program's foundation.

Men's team
The team was runner's up at the NCAA Men's Division I Cross Country Championship in 1988, 1995, 2013, 2019, and 2023.

Since 2016, the Northern Arizona men's team has been considered as the nation's leading program in NCAA Division I, winning a three-peat National Championship run from 2016 to 2018 and being undefeated in the regular season. The team has won 20 of the last 25 Big Sky team championships and won 17 of the last 25 Big Sky individual titles as of 2017. The team has been consistently ranked in the top 3 of the USTFCCCA national coach's poll since the start of the 2016 season. The team was the runner up in the 2019 national championship. In the first tie-breaker ever to win the National Championship, the Lumberjacks narrowly won the 2022 iteration of the National Championship over Oklahoma State University to complete another three-peat.

The 2017 repeat title closed out a perfect season with a 53-point victory, placing five athletes in the top 40. The victory was the lowest score (74) at the NCAA Championships since 2014, and the Lumberjacks became the first repeat champions since 2013–14. Director of Cross Country and Track and Field Mike Smith earned the Bill Dellinger Award as National Men's Coach of the Year and also picked up both the Big Sky's Men's and Women's Coach of the Year awards. In track and field, Smith was named the US Track & Field and Cross Country Coaches Association (USTFCCCA) Mountain Region Women's Indoor Coach of the Year in 2017 and 2018.

Women's team
The women's team was a national runner's up at the NCAA Division I Cross Country Championship in 2023 by 1 point behind North Carolina State.

Women's individual national championships (2)
 Men's Championship Results   Women's Championship Results 

Rivals
When Mike Smith became head coach in 2016 NAU turned into a national cross country powerhouse, developing a rivalry with the other nationally ranked leader, the BYU Cougars. NAU defeated BYU in the 2018 Championship while next year BYU defeated NAU in the 2019 Championship. The rivalry has been considered as "the best in a long time" and "the greatest in NCAA cross country history."

Media
The team was exclusively featured in the FloTrack documentary The Program: Northern Arizona that followed them in their championship 2016 season. The team was again featured in the five-part docuseries NAU: Running With The Boys that followed them throughout their 2019 season.

In 2023, former NAU runner Matt Baxter published Running Up the Mountain. The book chronicles the start of the Lumberjacks men's cross country dynasty as well as the team's connection to the Flagstaff community.