ABSTRACTThe author devised the Challenging Behaviour Scales (CBS) in response to the task of evaluating how much impact a ward‐based intervention had on the challenging behaviour of the men who lived there. They were used as one of a “battery” of ten research methods; adding a quantitative assessment to what were largely qualitative techniques. This paper aims to describe the CBS, as opposed to project outcomes, in the belief that it has potential for wider application within areas of evaluational research. The background and objectives of the CBS are outlined, along with a description of the construction of its two parts: the Frequency and Intensity sections.Production of the accompanying Manual is also described, as well as the reliability checks, scoring methods, and staff comments obtained after application of the CBS. Finally, suggestions are made about ways in which data produced from this model of scale development can be analysed, and the author clarifies the position that she believes this type of behavioural assessment has in evaluational work. Additional suggestions are made for people who may wish to use the model of construction underlying the CBS else