This paper will describe a method of documentary analysis used in a study examining the validity of clinical guideliness issued to health visitors to assist them in identifying families requiring increased health visitor support. This forms the preliminary work for a wider study examining how health visitors decide to increase support to vulnerable families. Although a number of published research texts dicuss the value of records and documents as important data sources for health service researchers, there is relatively little information avialable about the processes of documentary analysis. This paper offers one method for analysing clinical practice guidelines, it describes the development of a critique and analysis tool and expolres the strengths an weaknesses of this particular analysis instrument.