The configurations and operation of a field spectroradiometer (Exotech model 20‐B spectroradiometer) that measures the intensity of incident and reflected radiation from 0.37 to 2.52 &mgr; and emitted radiation from 2.76 to 13.88 &mgr; are described. The instrument was built by Exotech Inc. from specifications and plans developed by the USDA. Exotech contributed many engineering concepts basedupon knowledge of thetheory involved. The instrument consists of two systems, each made up of an optical unit and a control unit. One system covers the spectral range 0.37–2.52 &mgr;; the other system covers the spectral range 2.76–13.88 &mgr;. The optical units of the two systems mount side‐by‐side on a tiltable base mounted on an aerial lift truck. Separation between the objective lenses is about 30 cm to minimize parallax. The systems may be operated separately or in the tandem, boresighted mode. The control units are mounted in a camper‐type equipment van and are connected to the optical units by 60 m of armored cable. Preamplifiers and auxiliary electronics in the optical units are designed to operate without picking up interferences over this length of cable. The entire system is designed to operate in an outdoor environment. Provision has also been made for photographic annotation of field data setups.