This chapter explores how new techniques were developed to measure 'social impairment' in children in light of the Seebohm reforms of 1968 and other legal changes of the early 1970s. These led to major changes in the organisation of educational and social services. The closure of mental deficiency institutions in the wake of the 1959 Mental Health Act, the Seebohm reforms and the slow integration of all children into the education system were transforming ideas about social work. The new theory of autism and the autistic spectrum provided new models for thinking about human social development that were just as detailed and complex as those presented by the psychoanalysts. Lorna Wing's work was important because she developed a new theory of social development that held both political and scientific sway.