This technical presentation provides an overview of the specifications used to describe the accuracy of coordinate measuring machines (CMMs) along with the methods and tools used to calibrate CMMs in the field. The national and international standards used by all CMM manufacturers, including the ISO 10360 series, will be discussed. The history and purpose of standardized testing will also be briefly reviewed to provide understanding on how the calibration of CMMs differs from other measuring equipment. This presentation will also discuss the role of CMM calibration in traceability and show how Mitutoyo America provides traceability to CMM calibrations.