Attachment theory is essentially a child‐centred theory which is not readily adaptable to the relating of adults. Dependence is proposed as the adult equivalent of attachment. Both attachment and dependence have both a closeness‐seeking component and an upwardly directed component. From this observation emerges a theory of relating constructed around a horizontal axis concerning closeness seeking versus distance seeking and a vertical axis concerning upwardly directed behaviour versus downwardly directed behaviour. By the insertion of four intermediate positions, an octagonal arrangement of relating objectives is created which resembles the interpersonal circle. The theory differs from orthodox interpersonal theory in the clear distinction which is drawn between positive relating and negative relating. Three classes of negative relating are described. As in attachment theory, continuities are established between the relating of animals and the relating of humans. It is tentatively shown how the 10 DSM‐IV personality disorders might be accommodated within the structure of the octagon. Psychotherapy based upon interpersonal theory is described. Two instruments for measuring negative relating are described: the Person's Relating to Others Questionnaire, which is a general measure of relating, and the Couple's Relating to Each Other Questionnaire, which measures specifically interrelating within couples. The usefulness of these in measuring change in psychotherapy is illustrated.