Cassell originally committed to the Terps in March but almost immediately reneged on the choice in order to consider other schools, including South Florida and Pittsburgh.
"I thought I rushed into it, because I didn't get a chance to see any other schools," Cassell Jr. told the Washington Post. "But after I seen the other schools, I knew Maryland was the place to be."
Cassell joins a Terrapin class currently ranked No. 19 on ESPN.com and features center Shaquille Cleare (Houston/The Village School), small forward Jake Layman (Wrentham, Mass./King Philip), center Charles Mitchell (Marietta, Ga./Wheeler), guard Seth Allen (Fredericksburg, Va./Fredericksburg Christian) and center Damonte Dodd (Centreville, Md./Queen Annes County).