The unrivalled increase in human life expectancy over the last century has been one of the greatest achievements of public health medicine. However, it also poses new and unique challenges in health and social care, in particular the increased burden of chronic diseases and associated ageing states, including cognitive impairment and frailty. Understanding the occurrence and determinants of these ageing outcomes has become a global research priority with considerable policy implications. Several studies have been established in middle- and older-aged populations in the US (HRS, MIDUS) with the capacity to offer much- needed insights into these issues. However, it has recently become evident that the processes that underlie ageing states begin much sooner in the life course than originally thought, in some cases as early as birth or preconception. It is in such lif course-orientated studies that the USA is surprisingly bereft. The 1958 British Birth Cohort Study in the UK is the largest long-running study of this genre. With the study members approaching 60 years of age, when problems of ageing begin to emerge with frequency, we will carry out a detailed phenotypic and genotypic survey which covers an array of areas including biological, psychological, socioeconomic and behavioural characteristics. Uniquely, these new data will allow us to answer a series of important research questions of public health importance, ranging from identifying the policy-modifiable behaviours and biological mechanisms in mid-life that successfully reverse the effects of earlier life exposures and adversities on ageing outcomes, through to examining the long term influence of early life educational interventions on social, health, and ageing outcomes in older age, on to running a series of cross-country, and cross-cohort comparisons, to enable us to highlight where such processes are changing across generations, or between countries. These data will become publically available to bone fide population scientists soon after collection, so providing an unrivalled resource for the scientific community to investigate a range of policy- relevant issues.