The key to control of radionuclides in the environment is the ability to measure at least the lower guideline concentrations set by good environmental control practices. Rockwell Hanford Operations has developed and proposed field instrumentation systems that can give immediate, inexpensive, yet accurate, assays of guideline radionuclide concentrations in the environment. Field instrumentation is divided into two categories: (a) samples brought to a detector in the field (sa-de) and (b) a detector measuring activity in place (in situ). Guideline concentrations are established that field instruments should be able to detect to meet acceptable environmental standards. The guideline values cover environmental surface, subsurface, air, water, and decommissioning and decontamination (D&D). Plutonium is selected as an example: surface—0.060 nCi/g (0.010 nCi/cm2); subsurface—0.03 nCi/g at a 1- to 15-cm depth to 10 nCi/g at a >180-cm depth; airborne—2 × 10−12 μCi/cm3; water—5 × 10−6 μCi/cm3; D&D—surface of 150 nCi/cm2 nonsmearable. To meet the guidelines with in-field equipment, a helicopter survey, surface van, subsurface van, neutron activation, passive activation, and various portable (man-carried) systems have been used or tested at Hanford. The subsurface van was a first of its kind and is capable of obtaining 137Cs at pCi/g levels, plutonium at nCi/g, and many others at environmental level concentrations. Innovations have been added to most of the systems to improve practicability, accuracy, and sensitivity. New systems are being developed; others are planned.