Although the compound adjective ‘psychosocial’ was first used by academic psychologists in the 1890s, it was only in the interwar period that psychiatrists, psychologists and social workers began to develop detailed models of the psychosocial domain. These models marked a significant departure from earlier ideas of the relationship between society and human nature. Whereas Freudians and Darwinians had described an antagonistic relationship between biological instincts and social forces, interwar authors insisted that individual personality was made possible through collective organization. This (...) argument was advanced by dissenting psychoanalysts such as Ian Suttie and Karen Horney; biologists including Julian Huxley and Hans Selye; philosophers (e.g. Olaf Stapledon), anthropologists (e.g. Margaret Mead) and physicians (e.g John Ryle and James Halliday). This introduction and the essays that follow sketch out the emergence of the psycho-social by examining the methods, tools and concepts through which it was articulated. New statistical technologies and physiological theories allowed individual pathology to be read as an index of broader social problems and placed medical expertise at the centre of new political programmes. In these arguments the intangible structure of social relationships was made visible and provided a template for the development of healthy and effective forms of social organization. By examining the range of techniques deployed in the construction of the psychosocial (from surveys of civilian neurosis, techniques of family observation through to animal models of psychotic breakdown) a critical genealogy of the biopolitical basis of modern society is developed. (shrink)