R&C, part of Interpublic, said Black Sheep will operate as a business unit of the firm. Jenna Menking, who founded and served as president of BSSMG, takes a senior VP role with R&C reporting to CEO Tom Tardio.
Her eight-year-old firm has worked with olive oil producer Bertolli, Warner Bros., model Anne V and MySpace, among other clients, managing and creating social media accounts and campaigns.
Tardio said the deal meets "growing demands" in the social media space.
R&C rival PMK-BNC last week added social marketing shop Spokes Labs to create a digital unit it calls Vowel.