This project investigates theories of ‘transindividual’ processes of mind from the period 1890-1920 (including from Myers, Le Bon, Bergson, Butler and Scheler) in order to inform the study of ‘projective identification’ and ‘transgenerational trauma’ in contemporary social research. These concepts have been mobilised in numerous studies in the last twenty years of racial and ethnic conflict, and the after-effects of social trauma. However, their use within social research also meets with various challenges. These concepts were developed in psychoanalytic clinical work, and thus can be viewed by non-psychoanalytic social researchers as belonging to an alien paradigm. Another challenge concerns the limits of the psychoanalytic theoretical and descriptive languages themselves. Both concepts involve the theorisation of processes happening at transindividual levels (the passage of thoughts and feelings from one person to another, across social situations, or historically across generations). However such processes are hard to put across to researchers in disciplines informed by conventional assumptions about the bounded nature of individual experience, where thoughts and feelings belong to particular individuals, and cannot be ‘transferred’. In order to demonstrate the operation of such ‘transference’ via combinations of social, cultural and psychological mechanisms, psychoanalytically informed researchers have typically been led to couch their theorisation in quasi-occult terms (as intergenerational ‘haunting’, or the ‘possession’ of one mind by another). This research offers an innovative rethinking of the problems by turning to neglected strands of social and philosophical theory from 1890-1920. Here, psychological process is routinely approached within transindividual frameworks, using a variety of social, psychological and philosophical models. By rereading contemporary work on social trauma in the light of these earlier approaches, this research aims (1) to find better bridges between psychoanalytic and sociological forms of conceptualisation; (2) to develop alternative descriptive models of transindividual process, drawing from the historical basis of social theory.