A description is given of the procedures used and the results obtained in the operation of a color measurement laboratory equipped with the General Electric Recording Spectrophotometer. The calibrating procedures are based primarily on standards of the U.S. National Bureau of Standards, supplemented by 10 colored diffusing glasses, used primarily to test the reproducibility of reflectance measurements, and a new series of painted samples. Samples are used to examine instrument-to-instrument reproducibility of measurement.