The Red Sox activated Campbell (shoulder) from the 15-day injured list Thursday and optioned him to Triple-A Worcester, Christopher Smith of The Springfield Republican reports.
Campbell has been out for much of the season with a right shoulder impingement. He allowed just one unearned run with an 8:2 K:BB over 6.1 innings on his rehab assignment, but the Red Sox have elected to keep him at Worcester for the time being.