The National Institute of Standards and Technology (NIST) is distributing a Spanish-language CD-ROM providing training for the calibration of mass standards used for testing commercial measuring equipment. The free multimedia CD-ROM covers the same content taught in NIST's one-week basic mass metrology course for public and private sector metrologists. It duplicates an English language CD-ROM released last fall. Both CD-ROMs include interactive activities, knowledge quizzes, examples, video demonstrations, and specialty graphics and photos for specific products. The two CD-ROMs reflect NIST's commitment to advancing uniformity and harmonization in mass calibration measurements--critical to domestic and international commerce of everything from animal feed to automobile parts. Private and public sector metrologists interested in receiving the CD-ROM should contact owm@nist.gov with name and mailing information. Please stipulate "Spanish language Version" in the request. The English language version is also still available.