Saint Joseph's announced the deal Thursday after Jon Rothstein of CBS Sports first reported the agreement. He previously served as head coach of the Merchant Marine Academy Mariners and Navy Midshipmen.
The 47-year-old New Jersey native began his coaching career as an assistant at Philadelphia University in 1996. He also spent time as an assistant with the La Salle Explorers and had two stints with the Villanova Wildcats sandwiching his seven years leading the Navy program.
Lange, who's been a member of the Sixers' staff since 2013, compiled a 92-115 record with the Midshipmen. His teams finished above .500 only twice in seven seasons.
He enjoyed more success at the United States Merchant Marine Academy, a Division III program, including a 39-19 overall record and a trip to the D-III Sweet 16 in 2001.
In 2013, Lange turned down an opportunity to become head coach of the G League's Rio Grande Valley Vipers before he landed on the Philly staff.
He'll inherit a St. Joe's program that Phil Martelli led for the past 24 years. The school fired Martelli after the Hawks finished 14-19 in 2018-19. They went 6-12 in Atlantic 10 play and lost to Davidson in the quarterfinals of the conference tournament.
Although the Hawks will lose four seniors to graduation, Chris Clover was the only major contributor from that group. Lange will have some roster spots to fill alongside several key returning players as he attempts to hit the ground running in his return to the head coaching ranks.