Adolescents (10–19 years) and young people (20–24 years) continue to be vulnerable, both socially and economically, to HIV infection despite efforts to date. This is particularly true for adolescents — especially girls — who live in settings with a generalized HIV epidemic or who are members of key populations at higher risk for HIV acquisition or transmission through sexual transmission and injecting drug use. In 2012, there were approximately 2.1 million adolescents living with HIV. About one-seventh of all new HIV infections occur during adolescence. These guidelines provide specific recommendations and expert suggestions — for national policy-makers and programme managers and their partners and stakeholders— on prioritizing, planning and providing HIV testing, counselling, treatment and care services for adolescents.