This WHO guidance tool has been developed to help countries to systematically evaluate the functioning of their civil registration and vital statistics systems. The aim is to help countries develop a comprehensive understanding of the current system, identify weaknesses in the production and use of vital statistics, and provide the evidence base for corrective action. The application of the assessment tool will generate evidence that can be used in discussions with national governments, development partners and donors when seeking funding for the strengthening of the national civil registration and vital statistics systems.The WHO tool provides guidance on how to systematically evaluate all components of the national systems, from the legal framework supporting civil registration to the management and analysis of the data and their dissemination and use to guide policy-making. Particular emphasis is placed on the importance of undertaking a critical review of data quality, including consistency and plausibility checks. Statisticians, health planners and others involved in generating, analyzing and using vital statistics should be strongly encouraged and helped to develop such critical appraisal skills as an essential component of overall health information system development.