BackgroundMild-to-moderate depression in young people is associated with impaired social functioning and high rates of affective disorder in adult life. Earlier recognition of depression in young people has the potential to reduce the burden of depression in adulthood. However, depression in teenagers is underdiagnosed and undertreated. AimTo assess the usability and usefulness of a cognitive-behavioural-therapy-based technique for Therapeutic Identification of Depression in Young people (TIDY). Design and settingA qualitative study of four group practices in northwest London. MethodFace-to-face semi-structured interviews were conducted with practitioners who had been trained in the use of the TIDY technique. ResultsTwenty-five GPs and six nurses were interviewed. The key themes that emerged from the interviews were: practitioners were 'making sense of teenage depression' when interpreting signs and symptoms; the training in the technique was variable in its impact on practitioners' attitudes and practice; and time factors constrained practitioners in the application of the technique. ConclusionThe TIDY technique is usable in routine practice, but only if practitioners are allowed to use it selectively. This need for selectivity arises partly from concerns about time management, and partly to avoid medicalisation of psychological distress in young people. The perceived usefulness of the TIDY technique depends on the practitioner's prior knowledge, experience, and awareness. . 16 They specifically recommend that primary care professionals should be trained in the detection of depression but there has been little systematic study of how this can be achieved.There are two problems that must be overcome if the NICE guidelines are to be implemented. First, young people with psychological morbidity are difficult to engage in psychological therapies, 17 although such therapies appear to be effective in reducing symptoms and case prevalence. 18 Second, specialist child and young people's mental health services are already struggling to meet the demand for services. It is therefore important that specialist services are focused on those with the more severe disorder.Improved skills in primary care would improve identification of those with severe depression requiring referral, and facilitate intervention for mild-to-moderate depressive disorders within the primary care setting, thus broadening access to treatment for many young people. While there is at least one suitable and valid screening instrument for detecting depression in young people in primary care, 19 there is no solution to the problem of engaging young people in therapy.An approach that supports GPs in both identifying hidden psychological morbidity and engaging young persons in therapy ('therapeutic identification') in an opportunistic way during routine consultations would fit the NICE proposals.Such an intervention has been developed in a joint project between specialists in adolescent psychiatry and GPs, 20 and consists of a workplace-based trai...