Reid was the 14th player in school history taken in the NFL Draft. The only player selected earlier than the sixth round was Charlie Gogolak, a kicker who was taken in the first round in 1966.
Reid's college coach, Bob Surace, raves about his former player. Surace has called Reid a "tireless worker, dynamic leader."
Surace also told reporters that Reid helped Princeton win the Ivy League title last season "as much off the field as he did on the field."
The school's commencement ceremony is scheduled for Tuesday.
Reid, who earned his degree in sociology with a certificate in African-American studies, won't be the only Princeton alum around the Lions' headquarters.
Vice chairman Bill Ford Jr., whose family owns the team, is a 1979 graduate.
"His whole family has reached out to me," Reid said. "The Princeton family is a great family. Our Princeton alumni are great."
They haven't been so great in the NFL, but maybe Reid can help make that change.
The Lions signed defensive end Kalonji Kashama and receiver Cody Wilson while releasing defensive tackle Vaughn Martin and defensive end Kourtnei Brown.
Kashama (6-4, 270 pounds) impressed the coaching staff with his performance during a tryout at the recent rookie mini-camp. He made 5 1/2 sacks and nine tackles for loss last season for Eastern Michigan.
Wilson (Central Michigan) participated in training camp and was on the Lions' practice squad last season.