The MRC National Survey of Health and Development is the oldest and longest running continually-studied British birth cohort study, having followed a sample of 5,362 men and women born in England, Scotland and Wales since their birth in one week in March, 1946. During their childhood, the main aim of the NSHD was to investigate how the environment at home and at school affected physical and mental development and educational attainment. During adulthood, the main aim was to investigate how childhood health and development and lifetime social circumstances affected their adult health and function and how these change with age. Today, with study members in their seventies, the NSHD offers a unique opportunity to explore the long-term biological and social processes of ageing and how ageing is affected by factors acting across the whole of life.