In the week 3-9 March 1958, 98% of all births in England, Scotland and Wales (approximately 17,000) were studied in the Perinatal Mortality Survey. The follow-up of surviving children, known as the National Child Development Study, comprises four major sweeps at ages 7, 11, 16 and 23. Medical examinations were conducted at each age, except at 23 when health was self-reported. Details of the child's family background and socio-economic circumstances were recorded, together with assessments of their social development and educational attainment. Seventy-six per cent of the target population were interviewed at age 23. The health of subjects in the 1958 cohort has been described in over 200 publications but there is no comprehensive account of findings from birth to age 23. This overview attempts to redress this. As new data are gathered from the study subjects at age 33, opportunities will exist to investigate associations between childhood factors and health in midlife. Data on their partners and children will be included, allowing studies of inter-generational and family health. Further indications of changing illness patterns will be possible from comparisons with data collected on earlier and later born cohorts.