Attachment Theory was first developed by British psychologist John Bowlby in the mid-20th century. Bowlby’s work was groundbreaking as it highlighted the importance of early relationships and their impact on an individual's emotional development. He proposed that the bonds formed between infants and their primary caregivers play a critical role in shaping future relationships and emotional responses.

Key Figures: John Bowlby and Mary Ainsworth

John Bowlby is considered the father of Attachment Theory. His extensive research and clinical work laid the foundation for understanding how early attachment experiences influence emotional and relational health. Bowlby emphasized that children are biologically predisposed to seek proximity to their caregivers as a means of survival.

Mary Ainsworth, a developmental psychologist and a close colleague of Bowlby, expanded on his ideas through her empirical studies. She is best known for the "Strange Situation" study, which identified different attachment styles in children based on their responses to separation and reunion with their caregivers. Ainsworth’s work provided crucial evidence supporting Bowlby’s theory and introduced key concepts that are still used today.