This study examines the stability and change in attachment security from infancy to early adulthood over a 20-year period. Sixty white middle-class infants were assessed using the Ainsworth Strange Situation at 12 months of age, and 50 of these participants were re contacted and interviewed using the Berkeley Adult Attachment Interview (AAI) at 20-22 years of age. Overall, 72% of the infants maintained the same secure versus insecure attachment classification. Negative life events, such as parental loss, divorce, illness, psychiatric disorder, and abuse, were significant factors in changing attachment classifications. Fifty-six percent of infants whose mothers reported negative life events changed their attachment classifications, compared to only 28% of those without such events. The study supports Bowlby's hypothesis that attachment security can be stable across significant portions of the lifespan but remains open to revision based on experience. The findings highlight the importance of real-world experiences in shaping attachment representations and suggest that further research is needed to understand the mechanisms underlying stability and change.This study examines the stability and change in attachment security from infancy to early adulthood over a 20-year period. Sixty white middle-class infants were assessed using the Ainsworth Strange Situation at 12 months of age, and 50 of these participants were re contacted and interviewed using the Berkeley Adult Attachment Interview (AAI) at 20-22 years of age. Overall, 72% of the infants maintained the same secure versus insecure attachment classification. Negative life events, such as parental loss, divorce, illness, psychiatric disorder, and abuse, were significant factors in changing attachment classifications. Fifty-six percent of infants whose mothers reported negative life events changed their attachment classifications, compared to only 28% of those without such events. The study supports Bowlby's hypothesis that attachment security can be stable across significant portions of the lifespan but remains open to revision based on experience. The findings highlight the importance of real-world experiences in shaping attachment representations and suggest that further research is needed to understand the mechanisms underlying stability and change.