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 children in this survey are representative of all births in England, Wales and Scotland in March 1946. They are drawn from all social classes and during the first fourteen years of their lives less than 10 per cent of the children in 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.