How should one describe the identity of another, in ways which encompass both their idiosyncratic qualities and their group memberships or identifications, both of which can shift according to circumstance? Following on from the work of Kelly, Erikson, Tajfel and others Weinreich's Identity Structure Analysis (ISA), is "a structural representation of the individual's existential experience, in which the relationships between self and other agents are organised in relatively stable structures over time … with the emphasis on the socio-cultural milieu in which self relates to other agents and institutions" (Weinreich and Saunderson, (eds) 2003, p1)