She led Whitney Young High School in Chicago team to four consecutive city championships, including a state title in 2012 with a spotless 34-0 record. Last season alone she was a McDonald's All-American, a finalist for both the Naismith and McDonald's National High School Player of the Year awards and was named Chicago Sun-Times Player of the Year.
Harper - the highest-rated UK Hoops signee ever - might be accustomed to winning and she might know how it feels to receive awards, but wearing her country's colors and having a gold medal placed around her neck will never get old.
"It's a different feeling than winning the state championship or winning a big award," Harper said. "It's totally different because it's not just your state and it's not just your city; it's your entire country."
Harper got to experience just that on Sunday.
Playing at the U19 World Championship in Lithuania, Harper helped lead the United States to a 61-28 victory over France in the gold-medal game, tallying six points, three rebounds, two steals and an assist. With Harper averaging 8.4 points, 5.0 rebounds, 3.6 assists and 2.0 steals, the U.S. completed a 9-0 charge through the tournament.
"I think I was pretty consistent overall," Harper said. "My one thing was trying to the little things. Everybody on the team can score, everybody can play defense, but it's the little things that separate you."
That's something Harper knows from plenty of international experience. The gold medal she brought home this week is her third, as she played at both the 2012 FIBA U17 World Championship and 2011 FIBA Americas U16 Championship. The latest team, however, was exceptional.
"One thing about our team: We had a lot of depth," Harper said. "All 12 players are very versatile, can play multiple positions when needed. This was a special team, very talented from point guard all the way to the post. I think each player had a specific role and played their part and that's how we ended up winning the gold."
The team was comprised of six current collegians, three players bound for college and three high schoolers. The competition, as you might expect, was as fierce in practice as it ever was in games.
"Everybody wants to win and they're very intense," Harper said. "It helped me a lot playing with some of the players who are in college."
UConn's Breanna Stewart followed up on her Final Four Most Outstanding Player performance in the spring by leading the U.S. in scoring en route to MVP honors. College stars Bashaara Graves (Tennessee) and Alexis Jones (Duke) were also on the team, generating some inevitable trash talk.
"Here and there we would all make little comments, but it was all fun," Harper said. "We all knew that we're going to be competing against each other this year and when we were down there we were strictly U.S.A."
Even though Harper's focus was primarily on the gold medal, that didn't stop her from keeping up with her soon-to-be Kentucky teammates and coaches, including friend and former high-school teammate Janee Thompson, who is entering her sophomore season at UK. Playing on the national team kept her from coming on campus for the summer, but Harper doesn't think she'll have any trouble catching on when she arrives in Lexington on Aug. 24.
"They're all pretty cool," Harper said. "They keep me updated on what's going on in the summer, so I'm not really that behind."
Anything she may have missed in terms of conditioning or bonding with her new team will likely be more than made up for by competing against and playing with some of the best young players in the world.
Though she hasn't witnessed it firsthand just yet, Harper knows how different college is from high school and believes learning to play a role on a talented national team is experience that will pay off.
"In high school, you carry the team and you have players help you," Harper said. "With U.S.A., you have 11 other players that can help and are on the same level. I think on Kentucky, it will be the same way. But of course it will be a different concept because I'll be with my main team."
Harper still has to wait a little more than three weeks before joining her new team and admits to having some "jitters" about moving on to college. Her first priority will be making the adjustment to her new surroundings, but she has an ambitious goal in mind too.
"Eventually, one of my main goals is to become SEC Freshman of the Year," Harper said. "But that takes time over months. I'm not really focused on that right now. I'm focused on getting myself ready so I can be an asset to the team."