Five of Ball State's first seven shots were 3-pointers to build a 19-13 lead. Then the Cardinals outscored Grambling State 22-9 to close the half.
Ball State was 14 of 28 from 3-point range and made 54.5 percent of its 55 field goal attempts.
Telvin Marshall scored 16 points on 8-of-15 shooting for Grambling State (1-3). The Tigers had 18 turnovers and were out-rebounded 35-23.