Accurate measurement of radiation dose received by patients undergoing radiotherapy or medical imaging is essential for ensuring effective and safe healthcare. Equally, accurate measurement of radiation dose is required to guide employers in protecting their workforce from the harmful effects of ionizing radiation. Secondary Standards Dosimetry Laboratories (SSDLs) are specialist laboratories used to provide calibration and guidance for end users in hospitals and industry. This publication provides detailed technical information for countries on how to establish an SSDL, including planning processes, cost estimates and timelines. The technical descriptions and guidelines may also be helpful to existing SSDL radiation metrology staff when upgrading calibration facilities or purchasing new equipment.