This clinical practice guide covers best practice in the assessment and management of depression in young people (aged 12-25 years) as outlined in the relevant National Institute for Health and Care Excellence (UK) guidelines (www.nice.org.uk). The content aligns to the current diagnostic classifications of depressive disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; see www.psychiatry.org) and the International Classification of Diseases– 10th Revision (ICD-10; accessible at http://www.who.int/en/ in the Publications section). The focus is on assessing and managing major depressive disorder (MDD), persistent depressive disorder (dysthymia), and complex depression in young people. Complex depression includes “depression that shows an inadequate response to multiple treatments, is complicated by psychotic symptoms, and/or is associated with significant psychiatric comorbidity or psychosocial factors” (NICE, 2009; p.64). The DSM-5 includes two new depressive disorders: disruptive mood dysregulation disorder and premenstrual dysphoric disorder. Information is provided related to the assessment of these disorders, however the treatment of these disorders is not covered. This is because the current best-practice guidelines for managing depression in young people (NICE, 2009, NICE, 2005) do not yet include these disorders.