This child was enrolled at birth in a national survey which is being made by a Joint Committee of the Institute of Child Health, the Society of Medical Officers of Health and the Population Investigation Committee. The purpose of the present examination is to bring the medical and social history up to date. The children in this sample are representative of all births in England, Wales and Scotland. They are drawn from all social classes and during the first ten year of their lives only 8% of the original sample have been lost. The value of this inquiry depends on information being obtained for every possible survey child. The Joint Committee are therefore most anxious that this form should be completed.