The paper traces the relationship between attachment processes and the development of the capacity to envision mental states in self and others. We suggest that the ability to mentalize, to represent behavior in terms of mental states, or to have “a theory of mind” is a key determinant of self-organization which is acquired in the context of the child's early social relationships. Evidence for an association between the quality of attachment relationship and reflective function in the parent and the child is reviewed and interpreted in the context of current models of theory of mind development. A model of the development of self-organization is proposed which has at its core the caregiver's ability to communicate understanding of the child's intentional stance. The implications of the model for pathological self-development are explored, with specific reference to the consequences of maltreatment.