In this chapter I will delineate the ways in which the quality of early attachment relationships and actual experiences with the caregiver (s) form the building blocks for the representational world. I will begin by outlining the four basic assumptions of attachment theory, and then provide an overview of both past and more recent evidence that supports the theory. Development is looked at in the light of the attachment system. Developmental vicissitudes will be understood in the light of the manner in which basic attachments needs have been met by the caregiver (s). The concomitant effects of the maintenance or disruption of emotional bonds will be described.