In this article we summarize our current understanding of depression in older (14-18 years old) adolescents based on our program of research (the Oregon Adolescent Depression Project). Specifically, we address the following factors regarding adolescent depression: (a) phenomenology (e.g., occurrence of specific symptoms, gender and age effects, community versus clinic samples); (b) epidemiology (e.g., prevalence, incidence, duration, onset age); (c) comorbidity with other mental and physical disorders; (d) psychosocial characteristics associated with being, becoming, and having been depressed; (e) recommended methods of assessment and screening; and (f) the efficacy of a treatment intervention developed for adolescent depression, the Adolescent Coping With Depression course. We conclude by providing a set of summary statements and recommendations for clinicians.