Joey McLean, in his second start, added 13 points for the Dukes (15-11, 8-5 Colonial Athletic Association), who led by as many as 20 with about 5-1/2 minutes to play. James Madison shot 42 percent from the field with nine 3-pointers and outrebounded Delaware 36-30.
James Madison grabbed 11 steals and blanked Delaware 9-0 on second-chance points.
Delaware (6-18, 5-8) finished by sinking 8 of 8 free throws in the final 2:48 but missed its last three shots from the field, including a pair of 3-pointers. Chivarsky Corbett led Delaware with 17 points and Kyle Anderson, who surpassed the 1,200-point mark for Delaware, added 14.
The Blue Hens led 27-21 with 4:41 left in first half but James Madison went on a 35-11 run the next 16 minutes.