This paper is about the difficulties in working with the regressed or borderline patient. Drawing on clinical material, and recent empirical research on mother-infant interaction, theoretical explanations are considered. It is noted that these theories contain, by implication, guidance for psychotherapeutic practice. For patients functioning at this level of emotional development, techniques of traditional psychoanalysis are eschewed in favour of a ‘relational’ model, which draws on the therapist's capacity to be empathically engaged with the patient's internal and external world. Working in this way, it is argued, regressive periods can be seen as containing a potential for the patient's evolution of self.