SUPERVISION of psychotherapy began as the child of necessity in the early history of psychoanalysis and grew unselfconsciously until some 30 years ago, clearly establishing its value as a method of instruction. Casework supervision developed independently on the apprenticeship model but was markedly influenced by dynamic principles and psychoanalytic knowledge (Zetzel1), contributing much to the literature on supervision. Ekstein2 has described the ahistorical phase of psychoanalytic supervision, as well as the subsequent awakening of interest in and attention to the supervisory experience. Over the past 30 years a considerable literature has developed on the subject. The purpose of this paper is a critical assessment of this literature as it bears on the supervision of psychiatric residents and on research in supervision. A review of the literature reveals a general preoccupation with several essential issues: (1) What kind of data are