The objective of this Handbook is to explain concepts and provide approaches to the following aspects of the production of reference materials - (a) the assessment of homogeneity; (b) the assessment of stability and the management of the risks associated with possible stability issues related to the properties of interest; (c) the characterization and value assignment of properties of a reference material; (d) the evaluation of uncertainty for certified values; and (e) the establishment of the metrological traceability of certified property values.