The survey is carried out by the School Health Research Network (SHRN). SHRN is a partnership led by the Centre for the Development and Evaluation of Complex Interventions for Public Health Improvement (DECIPHer) at Cardiff University, with Welsh Government; Public Health Wales; Cancer Research UK; and the Wales Institute of Social and Economic Research, Data and Methods (WISERD). The SHW survey is a biennial cross-sectional survey administered to 11-18 year olds attending SHRN member schools and was developed from the World Health Organisation’s Health Behaviour in School aged Children (HBSC) survey. The survey is combined with a School Environment Questionnaire, which all schools complete on their health policies and practices. The student survey provides in-depth understanding of the health and wellbeing of young people, including the whole population and subgroups of the population. Content includes: mental health and wellbeing, substance use and gambling, physical activity and diet, school life, family and social life, and relationships.