Summary: At frequencies in the GHz range, an electrical connector must be considered as part of an electromagnetic transmission line. This paper reviews the effect of signal frequency on constriction resistance, interfacial capacitance and contact inductance at an electrical interface in a high speed connector. The deleterious effects of contact degradation at pin-receptacle junctions on transmitted signal integrity, are addressed. For frequencies in the GHz range, an electrical interface becomes capacitively coupled if contact resistance increases sufficiently. Contact deterioration may also lead to the generation of parasitic third-order harmonics that contribute to loss of signal integrity.