This report is intended to serve those who are establishing or operating calibration facilities for radiation monitoring instruments. The sources of radiation and associated apparatus and calibration techniques presented are examples of what established calibration laboratories have deemed adequate. However, these are not to be considered as the only suitable methods and instruments available for proper calibration. The reader’s attention is drawn to the bibliography for a list of documents, which also covers other calibration techniques. Because of the multitude of applications for radiation monitoring instrumentation, e.g. in medicine, radiography or agriculture, it is impossible to describe the complete calibration of all instruments in one report. However, the considerations described here should serve as a basis for calibrating radiation protection instruments. In addition to presenting a description of calibration facilities and procedures, this Safety Report includes appropriate definitions and describes appropriate methods for the statement of uncertainties in measurements. An example of a calibration