This paper describes the essence of object relations theory as developed by Winnicott through his concepts of the transitional object, the good enough mother holding a situation for her child and play both solitary and mutual. These concepts are compared and contrasted with the essential features of attachment theory as put forward by Bowlby.It is suggested that Winnicott's object relations concepts and attachment theory each provide a framework to explain similar psychological and interpersonal phenomena. Reasons are put forward for the choice of attachment theory as a basis for family therapy and to suggest hypotheses to investigate the quality and quantity of intrafamilial social interaction and concomitant emotional states.The family in family therapy is described in terms of the interpersonal dynamic suggested by attachment theory. The family is seen as a homoeostatic system of relationships between individuals at different stages of development who share set goals aimed at terminating a specific form of proximity‐seeking attachment behaviour and promoting exploratory behaviou