Health Behaviour in School-aged Children (HBSC) is a cross national research study conducted in collaboration with the World Health Organisation (European Office). The study runs on a four-year cycle and in 2006 there were 41 participating countries across Europe and North America. HBSC collects data on key indicators of health, health attitudes and health behaviours, as well as the contexts of health for young people. The study is a school-based survey with information collected from students through self-completion questionnaires in classrooms.