John Bowlby bemoaned the separation between the biological and psychological approaches in psychiatry, and hoped that attachment theory, which brings together psychoanalysis and the science of ethology, would help bridge the rift between them. Recent findings in developmental psychology have delineated features of parent-infant interaction, especially responsiveness, attunement, and modulation of affect, which lead to either secure or insecure attachment. Similar principles can be applied to the relationship between psychotherapist and patient--the provision of a secure base, the emergence of a shared narrative ('autobiographical competence'), the processing of affect, coping with loss--these are common to most effective psychotherapies and provide the basis for a new interpersonal paradigm within psychotherapy. Attachment theory suggests they rest on a sound ethological and hence biological foundation.