The dialectic in psychoanalysis between theories about the mutative effects of interpretation and psychological knowledge and those concerning the effects of interpersonal interaction constitutes an important tension for approaches to psychoanalytic technique. This essay briefly summarises the thinking around these alternative conceptualisations of therapeutic action, and introduces a new empirically derived model, that of 'repetitive interaction structure', which attempts to bridge therapeutic action by insight and by relationship. Interaction structure is a way of formulating those aspects of the analytic process that have come to be termed intersubjectivity, transference-countertransference enactments and role responsiveness. The concept operationalises important aspects of interpersonal interaction, and can help specify the two-person patterns that emerge in an analysis. Patient and analyst interact in repetitive ways; these patterns of interaction, which are slow to change, probably reflect the psychological structure of both patient and analyst, whether psychic structure is conceptualised in terms of object-representations or compromise formations and impulse-defence configurations. Therapeutic action is located in the experience, recognition and understanding by patient and analyst of these repetitive interactions. Interaction structures stress the importance of the intrapsychic as a basis for what becomes manifest in the interactive field. Clinical illustrations from a psychoanalysis are provided, and research on repetitive interaction structures is described.