The purpose of this paper is to present the results of research to improve the definitions and methods for delineating the basic statistical units in a census of residential juvenile facilities. The concepts defining the target statistical unit in this census--“facility” and “facility type”--will be discussed and the questions eliciting this information on the mailout form will be shown. Six factors affecting how respondents interpret these concepts and apply them to their own organizations to determine their reporting units will be identified. The interaction of these factors will be illustrated in general diagrams of facility layouts and arrangements. The implications of these interactions for the fit between the target statistical units intended in this census and the units respondents choose to report on will he discussed. The implications for frame coverage, data quality, data collection methodology, respondent burden and questionnaire revisions will be identified. Finally, the applicability of the findings to other group quarter and business surveys will be addressed.