A receptacle assembly includes a contact module having a conductive holder and a frame assembly received in the conductive holder and electrically shielded by the conductive holder. The frame assembly has a plurality of receptacle signal contacts having mating portions extending from the conductive holder. The receptacle signal contacts are arranged in differential pairs carrying differential signals. Ground shields are received in the conductive holder between the frame assembly and the conductive holder. The ground shields have grounding beams extending along the mating portions of the receptacle signal contacts. The grounding beams are arranged on four sides of each differential pair of the receptacle signal contacts.