Sills (back/rib) participated in OTAs on Tuesday, John Schmeelk of the Giants' official site reports.
Sills returned to action after getting injured during a practice session in late May. The 27-year-old registered 11 catches for 106 yards in nine games last season, but he could find his roster spot in jeopardy, as New York's receiving room has become a lot more crowded throughout the offseason.