BACKGROUND: The management and detection of depression varies widely, and the causes of variation are incompletely understood. AIMS: To describe and explain general practitioners' (GPs') current practice in the recognition and management of depression in young adults, their attitudes towards depression, and to investigate associations of GP characteristics and patient sex with management. METHOD: All GP principals in the Greater Glasgow Health Board were randomized to receive questionnaires with vignettes describing increasingly severe symptoms of depression in either male or female patients, and asked to indicate which clinical options they would be likely to take. The Depression Attitude Questionnaire was used to elicit GP attitudes. RESULTS: As the severity of vignette symptoms increased, GPs responded by changing their prescribing and referral patterns. For the most severe vignette, the majority of GPs would prescribe drugs (76.4%) and refer the patient for further help (73.7%). Male and female patients were treated differently: GPs were less likely to ask female patients than male patients to attend a follow-up consultation (odds ratio [OR] = 0.55), and female GPs were less likely to refer female patients (OR = 0.33). GPs with a pessimistic view of depression, measured using the 'inevitable course of depression' attitude scale, were less willing to be actively involved in its treatment, being less likely to discuss a non-physical cause of symptoms (OR = 0.77) or to explore social factors in moderately severe cases (OR = 0.68). CONCLUSIONS: Accepting the limitations of the method, GPs appear to respond appropriately to increasingly severe symptoms of depression, although variation in management exists. Educational programmes should be developed with the aim of enhancing GP attitudes towards depression, and the effects on detection and management of depression should be rigorously evaluated.