A probe station is equipped with an integrated guarding system which facilitates the use of the station for low-current measurements, as well as integrated Kelvin connections to eliminate voltage losses caused by line resistances. The station has a chuck assembly which consists of at least three chuck assembly elements. A first element supports the test device, while an underlying second element acts as a guard to reduce leakage currents. These elements are electrically insulated from each other and from their underlying supporting structure, which is the third element. Ready-to-use, selectively detachable electrical connector assemblies provide for signal and guard connections to the first and second chuck assembly elements, respectively, as well as providing Kelvin connections thereto. The capacitance between the respective chuck assembly elements is extremely low due to the provision of air space as the primary electrical insulator. Unique electrical connectors for individually-positionable probes provide both guarding and Kelvin connection capability together with separate EMI shielding movable in unison with each probe individually.