Clinical practice guidelines are one of the main tools by which clinicians, policy makers and patients hope to make health care less variable, more reliable and efficient, but there is little understanding of the processes by which clinical guidance is put together by guideline groups. This paper describes the social organisation of knowledge within clinical practice guideline development processes by drawing on the sociology of situated judgement. Two guideline development processes were observed, and the development group meetings (N = 21) recorded and analysed qualitatively. Data analysis suggested that clinical guidance comes to existence through the combination of repertoires of evaluation, organised around four different epistemic criteria: robustness, usability, acceptability and adequacy. This research provides a detailed and layered understanding of the knowledge dynamics involved in developing recommendations for appropriate health care for specific clinical circumstance.