From the publication of the first studies revealing GPs' apparent inadequacy at identifying and treating patients with depression, mental health has dominated the primary care research agenda. Much effort has been expended to find a way of transmuting yesterday's erratic GPs into tomorrow's infallible diagnosticians. But for the most part this philosopher's stone has eluded discovery. On page 665 a group in New Zealand document the effect of systematic case finding. The authors conclude that it is unlikely to be a useful approach, illustrating the difficulties of using screening instruments that are always imprecise. They also found that the doctors in the study were better at spotting depression in patients they already knew, placing the discussion, in their phrase, ‘within the context of general practice continuity of care.’ The accompanying leader takes up this aspect, with the statement that ‘the diagnosis of a mental health disorder … evolves in a …