Census microdata consist of records of persons, households and dwellings as recorded in quinquennial, or more commonly decennial, enumerations of national populations. Census metadata are the documentation which describe each census: forms, manuals, data dictionaries, codebooks, technical reports, etc. Beginning with the 1960 round of population censuses, statistical offices began to disseminate anonymized samples of census microdata, but access was often limited to researchers resident in the country. Over the decades the number of statistical offices offering census samples—and their availability world-wide—increased, so that with the 2000 round, almost all statistical offices plan to disseminate such samples. What has not changed is the metadata. These are typically limited to a data dictionary to describe the record structure as well as codes and labels of the microdata. As far as I am aware, no statistical agency has attempted to re-write or restructure metadata for historical census microdata to attain standards of the 21st century.