The Welsh Health Survey informs local government, NHS, and nationwide health strategy. The Welsh Health Survey (WHS) collects information on the health and health-related lifestyles of people living in Wales. It is a major source of information about the health of people in Wales, the way the NHS is used, and behaviours that can affect health, such as smoking and alcohol consumption. Data for the WHS is collected via face-to-face-interviews and self-completion questionnaires. The sampling unit for the WHS are households, however all adults within households were asked to take part. Families with children under the age of 16 are eligible, however where the household has 3 or more children, up to two children between the ages of 0 and 15 are randomly selected for inclusion in the study. Interviews are used to collect data at the household level, with questionnaires distributed to household members. Information on the household type and employment status of the household reference person are collected, and the interviewer is asked to comment on the condition of the property. Separate self-completion questionnaires are used to collect data for adults and young people (aged 13-15), whilst adults/guardians are required to complete questionnaires on behalf of children younger than 13 years old. The WHS data, as provided via the UK Data Archive, is split into two separate datasets, these relating to adults – 16 and older – and children. The WHS can be analysed at both the individual and household level, with appropriate weights being supplied for each. The dataset provides a household identifier which allows for adult-child records to be combined for research exploring ‘household’ health or the links between parental and child health, for example.