This publication’s main purpose is to provide guidance to the producers of population and housing censuses on how to assess the quality of administrative data for use in a census. The Guidelines cover the practical stages of assessment, from working with an administrative data supplier (or administrative authority) to understand a source, its strengths, and limitations, all the way to the receipt and analysis of the actual data. The Guidelines cover key quality dimensions on which an assessment is made, using various tools and indicators. For completeness, the Guidelines also include information about the processing and output stages of a census, with respect to the use of administrative sources.