Shrewsberry, who served three seasons with Purdue, will join new Celtics head coach Brad Stevens, whom he served under with Butler. He is the first hire of Stevens' new coaching staff in Boston.
Shrewsberry, 37, started as Butler's coordinator of basketball operations before becoming an assistant coach in 2008. He helped build a team that appeared in two national championship games. However, like Stevens, he has never worked in the NBA.
Just Thursday morning, Shrewsberry was on the recruiting trails in Indianapolis for the Adidas Invitational. Now, Purdue must add to its coaching staff during the important open evaluation period.