His brother Miles had originally committed to play at Stanford, but chose to follow him to Duke after Stanford coach Trent Johnson left for LSU.
 Mason was elated, as they had been in boarding school together, and never really spent much time apart.

He missed the first six games of the 2009–10 season with a broken left wrist.
 He and Miles usually rotated into games together, replacing Brian Zoubek and Lance Thomas, and were often the first two players off the bench.
 Teammate Nolan Smith said:  "He's an athlete.
He can run and jump with the best of them in the country."

Through April 4, 2010, Mason was tied for first on the team in blocks, with 30, and second on the team with 21 dunks.
 In an average 14.1 minutes of play per game during the 2009–10 season, he averaged 3.1 rebounds and .9 blocks.

Coach Mike Krzyzewski said: "Mason has got a chance to be really, really good.
He has skills of a guard and the body of a big man, and a great basketball mind.
He's very competitive, he likes the stage, and he's comfortable with the ball."

It was anticipated that in 2010–11 the two brothers would both be in Duke's starting lineup.
 Georgia Tech coach Paul Hewitt viewed Mason as Duke's best pro prospect.
 Told in early April 2010 that some scouting services viewed him as the team's best pro prospect, Plumlee said: "I have seen that.
I don't even really know what to say to those people.
I mean, let's be real.
I'm trying to play the best I can, but in reality nobody goes from the bench to the NBA.
Come on."

Mason started 11 of the team's first 13 games in the 2010–2011 season, in 3 of which he recorded double doubles in points and rebounds.
For the season, he averaged 7.5 points, 8 rebounds, and 1.5 blocks per game to help man the paint for the defending champion Blue Devils.

He was a 2012–13 first team Academic All-American selection.
He was also a 2012–13 Senior CLASS Award finalist.
His brother Miles had originally committed to play at Stanford, but chose to follow him to Duke after Stanford coach Trent Johnson left for LSU.  Mason was elated, as they had been in boarding school together, and never really spent much time apart.
He missed the first six games of the 2009–10 season with a broken left wrist.  He and Miles usually rotated into games together, replacing Brian Zoubek and Lance Thomas, and were often the first two players off the bench.  Teammate Nolan Smith said:  "He's an athlete. He can run and jump with the best of them in the country."
Through April 4, 2010, Mason was tied for first on the team in blocks, with 30, and second on the team with 21 dunks.  In an average 14.1 minutes of play per game during the 2009–10 season, he averaged 3.1 rebounds and .9 blocks.
Coach Mike Krzyzewski said: "Mason has got a chance to be really, really good. He has skills of a guard and the body of a big man, and a great basketball mind. He's very competitive, he likes the stage, and he's comfortable with the ball."
It was anticipated that in 2010–11 the two brothers would both be in Duke's starting lineup.  Georgia Tech coach Paul Hewitt viewed Mason as Duke's best pro prospect.  Told in early April 2010 that some scouting services viewed him as the team's best pro prospect, Plumlee said: "I have seen that. I don't even really know what to say to those people. I mean, let's be real. I'm trying to play the best I can, but in reality nobody goes from the bench to the NBA. Come on."
Mason started 11 of the team's first 13 games in the 2010–2011 season, in 3 of which he recorded double doubles in points and rebounds. For the season, he averaged 7.5 points, 8 rebounds, and 1.5 blocks per game to help man the paint for the defending champion Blue Devils.
He was a 2012–13 first team Academic All-American selection. He was also a 2012–13 Senior CLASS Award finalist.
Mason Plumlee