Unlike most psychoanalytic concepts, parapraxis has seen little systematic debate since first being propounded 120 years ago in The Psychopathology of Everyday Life. In this article, the authors first outline the psychoanalytic understanding of human error, beginning with Freud's view of parapraxes as being determined by repression, regulation of unpleasure, unconscious conflicts, associative links, and a series of conducive and inhibiting conditions. Then the authors debate whether this psychoanalytic understanding of errors can withstand empirical investigation. A review of the evidence from experimental psychology, accident research, and psychotherapy research seems to support psychodynamic hypotheses to some extent.