The nature and effects of stigma have been widely discussed in the context of mental illness, and references to stigma are commonly used to explain a wide array of social processes. For example, it is often claimed that stigmatisation affects aspects of personal identity, that it underpins unjust and discriminatory behaviour, and that it is responsible for a reluctance among members of the lay public to disclose the presence of treatable psychiatric symptoms and problems to health professionals. A widespread reluctance to disclose symptoms of 'emotional problems' to health professionals is in fact well documented. Yet the reasons for such patterns of behaviour are far from clear. However, in this paper, on the basis of qualitative data collected from primary care attendees in Wales (N=127), the authors suggest that appeals to stigma are inadequate to explain the phenomenon. More likely, it seems, is that members of the lay public have markedly different images from health professionals of what constitutes a mild to moderate psychiatric problem. Consequently, it is argued that the phenomenon of non-disclosure could be viewed more accurately as a problem of alternative taxonomic systems than of fear of stigma. The implications of the argument for health practice and theory are outlined.