a wafer probe station is equipped with an integrated environment control enclosure substantially surrounding a supporting surface for holding a test device , such enclosure limiting fluid communication between the interior and exterior of the enclosure and preferably also providing emi shielding and a dark environment . the limited communication between the interior and exterior of the enclosure is kept substantially constant despite positioning movement of either the supporting surface or probe holders . the positioning mechanisms for the supporting surface and probe holders each have portions located at least partially outside of the enclosure for transferring movement mechanically to the surface or holders , respectively .