Harrison Barnes was rated as the number 1 player in the class of 2010 by Scout.com and in the ESPNU 100.
He was rated as the number 2 player by Rivals.com.
In his junior year, Barnes and teammate Doug McDermott led Ames High School to an Iowa 4A state championship where he had 24 points and 8 rebounds in the final, capping off a 26–0 season.
In his senior year, Barnes and McDermott led Ames to a 27–0 season and a second straight Iowa 4A state championship becoming Iowa's big-school class's first team to go undefeated in consecutive seasons.
In the finals he scored 19 points against Southeast Polk.
He averaged 27.1 points, 10.4 rebounds, 4.0 steals and 4.0 assists during his senior year and was selected to the USA Today All-USA First Team.
Barnes capped off his Ames High School career as their all-time leading scorer with 1,787 points.
Barnes played in the 4th annual Boost Mobile Elite 24 Hoops Classic where he scored 18 points for Skip to My Lou.

On January 20, 2010, it was announced that Barnes was selected to the 2010 Junior National Select Team.
The team played at the 2010 Nike Hoop Summit at the Rose Garden in Portland, Oregon, on April 10.
He was also selected to play in the 2010 McDonald's All-American Game where he led the West team to a 107–104 victory.
He scored a team high 18 points and was named co-MVP with Jared Sullinger.
He also played in the 2010 Jordan Brand Classic where he was named co-MVP with Kyrie Irving.
On March 10, 2010, Barnes won the Morgan Wootten Player of the Year Award, which goes to the nation's top player.

Barnes completed nine advanced placement credits before graduating high school.
Harrison Barnes was rated as the number 1 player in the class of 2010 by Scout.com and in the ESPNU 100. He was rated as the number 2 player by Rivals.com. In his junior year, Barnes and teammate Doug McDermott led Ames High School to an Iowa 4A state championship where he had 24 points and 8 rebounds in the final, capping off a 26–0 season. In his senior year, Barnes and McDermott led Ames to a 27–0 season and a second straight Iowa 4A state championship becoming Iowa's big-school class's first team to go undefeated in consecutive seasons. In the finals he scored 19 points against Southeast Polk. He averaged 27.1 points, 10.4 rebounds, 4.0 steals and 4.0 assists during his senior year and was selected to the USA Today All-USA First Team. Barnes capped off his Ames High School career as their all-time leading scorer with 1,787 points. Barnes played in the 4th annual Boost Mobile Elite 24 Hoops Classic where he scored 18 points for Skip to My Lou.
On January 20, 2010, it was announced that Barnes was selected to the 2010 Junior National Select Team. The team played at the 2010 Nike Hoop Summit at the Rose Garden in Portland, Oregon, on April 10. He was also selected to play in the 2010 McDonald's All-American Game where he led the West team to a 107–104 victory. He scored a team high 18 points and was named co-MVP with Jared Sullinger. He also played in the 2010 Jordan Brand Classic where he was named co-MVP with Kyrie Irving. On March 10, 2010, Barnes won the Morgan Wootten Player of the Year Award, which goes to the nation's top player.
Barnes completed nine advanced placement credits before graduating high school.
Harrison Barnes