Williams, pressed into service with starter Steven Jackson's lingering quad injury, has rushed for 127 yards on 32 carries in two games this season -- both Rams losses.
Jackson, who did not play last Sunday and was held out of practice on Wednesday, was able to take limited reps on Thursday.
Defensive end C.J. Ah You also returned to practice Thursday, albeit on a limited basis as he continues to recover from a wrist injury.
Tight end Michael Hoomanawanui also took limited reps for the second day in a row.