Fifty-one years have elapsed since the Report of the Royal Commission on the Care and Control of the Feeble-minded was published and paved the way for the Mental Deficiency Act of 1913. Since that time two developments have taken place. On the one hand the administrative procedures for dealing with defectives on the basis of the Act and its amendments have been clearly defined and formalized. On the other there has been a continuous development and expansion of our social and welfare services. These developments, which should have been complementary in their aims, have in fact often proved conflicting in effect, because mental deficiency until very recently was bound to outmoded procedures which were designed to segregate the defective from the community rather than to integrate him with it, and give him the opportunities for re-socialization which our modern welfare services afford. The original belief that a hereditary neuropathic diathesis lay at the root, of most of our social ills and would sooner or later lead to national degeneracy has been replaced by scientific genetic studies, and by medical research into the aetiology of the condition, and the associated problems involved in the training and employability of the defective. Increasing professional and public recognition of the inherent faults of existing mental deficiency legislation led to the setting up of the Royal Commission on the Law Relating to Mental Illness and Mental Deficiency which published its report in May, 1957, and this in its turn has prepared the way for the Mental Health Bill which is at present in the final stages of its passage through Parliament.