The aim of this paper is a thorough explication of the concept of identity. We have synthesized the scattered psychiatric and psychoanalytic literature on the topic to shed light on the historical origins, development, phenomenology, clinical relevance, and methods of assessing identity. Our review revealed that: (I) The concept of identity has persisted over eight decades. (2) Identity originates in the earliest interplay of the infant's temperament with the mother's attitude, gains structure from primitive introjections, refines itself through later selective identifications, acquires filiation and generational continuity in passage through the Oedipus complex, and arrives at its more or less final shape through synthesis of contradictory identifications and greater individuation during adolescence. It remains subject to further refinements during young adulthood, midlife, and even old age, (3) A cohesive identity comprises a realistic body image, subjective self-sameness, consistent attitudes, temporality, gender, authenticity, and ethnicity. (4) Disturbance of identity suggests psychopathology, with greater identity disturbance being associated with more-severe conditions (e.g., severe personality disorders, multiple personality, psychosis). (5) Clinical and psychometric assessment is therefore relevant and might indicate treatment strategies and outcome expectations. Findings from the literature are elucidated, and areas needing further research are identified.
