Attachment theory is the joint work of John Bowlby and Mary Ainsworth (Ainsworth & Bowlby, 1991). Drawing on concepts from ethology, cybernetics, information processing, developmental psychology, and psychoanalysis, John Bowlby formulated the basic principles of the theory. In doing so he revolutionized our way of thinking about the child's bond with the mother and its breakdown through separation, deprivation and mourning. Mary Ainsworth's innovative methodology not only made it possible to empirically test some of Bowlby's ideas, but also helped expand the theory itself and is responsible for some of the new directions it is now taking. Ainsworth contributed to the concept of the attachment figure as a secure base from which a child can explore the world. Furthermore, he formulated the concept of maternal sensitivity to infant signals and its role in the development of mother-infant attachment patterns (Bretherton, 1985). Bowlby's main conclusion, based on the available empirical evidence, was that to grow up mentally healthy, “the infant and child should experience a warm, intimate, and ongoing relationship with the mother (or permanent mother substitute) in which both find satisfaction and enjoyment” (Bowlby, 1951). Relationship-based learning evolves from the constructs of attachment theory. In typical early development, relational experiences between infant and mother (or primary caregiver) have survival significance and facilitate the infant's exploration of the world. Within these early experiences, caregivers engage in a sensitive, reciprocal, synchronous, and empathetic response to their infants. These ongoing and attuned interactions lead to secure attachment (Bowlby, 1969, 1988). Research has shown that positive results... half of the article...ademic Press.Mahoney,G. (1991). Responsive parenting: A relationship model for early intervention. Paper presented at the Conference of Gulf States in Early Intervention, Point Clear, AL.McLeod, SA (2008). Mary Ainsworth | Attachment styles. Retrieved from http://www.simplypsychology.org/mary-ainsworth.htmlSiegel, D. (1999). The developing mind: Toward a neurobiology of interpersonal experience. New York, Guilford Publications. Tizard, B., & Joseph, A. (1970). Cognitive development of young children in residential care: A study of children aged 24 months. Journal of Child Psychology and Psychiatry, 11: 177-186. Wetherby, A. M., Prizant, B. M., & Schuler, A. L. (1997). Improving language and communication: theoretical foundations. In D. Cohen & F. Volkmar (Eds.), Handbook of autism and pervasive developmental disorders (2nd edition.)