Anderson finished with 17 points, Williams had 16, and Jones added 11 for Robert Morris (8-4), which hit 13 of 27 attempts from 3-point range.
There were seven lead changes and four ties over the first 6 minutes of the first half before Jones broke open a 16-all game with a 3-pointer. The Colonials led by at least two the rest of the half and took a 40-34 lead into intermission.
Louisiana-Lafayette (4-8) rallied to take a 52-47 lead in the second half but Williams, Anderson, and Russell Johnson hit consecutive 3-pointers to put Robert Morris up for good, 56-52, with 8:02 left to play.
Mbamalu Bryant led Louisiana-Lafayette with 21, Elfrid Payton had 19 but the Ragin' Cajuns hit just 8 of 17 free throws.
Forward Kennedy Meeks, who has averaged 9.4 points and 6.5 rebounds at North Carolina, has pulled out of the NBA draft and will return to the Tar Heels.
Cal big man Ivan Rabb could have been selected in the top 10 of the NBA draft. Instead, he's returning to Berkeley to make himself, and the Golden Bears, stronger.
Devin Williams' decision last month to sign with an agent and enter the NBA draft has left West Virginia in a tough spot.