A high frequency electrical connector including a plastic housing and a plurality of contacts retained by the plastic housing. The contacts include a plurality of differential pair signal contacts and a plurality of grounding contacts beside the signal contacts, respectively. The plastic housing includes the insulative plastic portion and the conductive plastic portion to which the insulative plastic portion is assembled. The signal contacts are retained in the insulative plastic portion while the grounding contacts are retained in the conductive plastic portion wherein the signal contacts are isolated from the conductive plastic portion via the insulative plastic portion.