Recovery, defueling, and restoration of Three Mile Island Unit 2 (TMI-2) to an environmentally stable configuration has been a labor-intensive effort that had to be conducted in complex radiological conditions of varying field intensities. Part of the success of the TMI-2 Radiological Controls Program in minimizing worker exposure can be attributed to the effective use of a variety of portable instruments. Systematic surveys were conducted to quantify general radiation fields, locate hot spots, and establish surface contamination levels and airborne concentrations of radionuclides. Detailed and accurate radiological surveys and field measurements are essential to as low as reasonably achievable reviews, radiation work permit specifications for protective measures, and job briefings. Radiological instruments used at TMI-2 include a variety of devices capable of assessing radiation fields from sealed sources, contaminated surfaces, and airborne radioactivity. A major effort in the recovery process was the systematic characterization of contamination levels throughout the reactor and auxiliary buildings. At TMI-2, a fast sorting measurement technique was developed to identify and prioritize surfaces for exposure reduction and to rapidly evaluate effectiveness of decontamination efforts. Standard vendor-supplied instruments such as the Eberline HP-220-A and the RO-7 had to be modified in their respective directional sensitivity. Decontamination techniques also required extensive monitoring for airborne levels of various radionuclides. Area air samples and breathing zone air samplers were used extensively to assess for potentially respirable radioactivity. To optimize detection of personnel skin and clothing contamination, pancake probe friskers were largely replaced or supplemented by automated personnel contamination monitors. At TMI-2, the maintenance and calibration of radiological instruments are conducted on-site by a group of qualified technicians who are an integral part of the Radiological Controls Division. All calibration and repair are subject to a variety of audits, inspections, and internal and external assessments. Quality assurance auditors routinely verify compliance with station procedures, ensure that primary instruments are sent to accredited laboratories for calibration, and certify that calibration sources are traceable to the National Bureau of Standards.