High Quality Content by WIKIPEDIA articles! Attachment theory describes the dynamics of long-term relationships between humans. Its most important tenet is that an infant needs to develop a relationship with at least one primary caregiver for social and emotional development to occur normally. Attachment theory is an interdisciplinary study encompassing the fields of psychological, evolutionary, and ethological theory. Immediately after WWII, homeless and orphaned children presented many difficulties, and psychiatrist and psychoanalyst John Bowlby was asked by the UN to write a pamphlet on the matter. Later he went on to formulate attachment theory.