After carefully examining various cases of maladjusted children, psychologist John Bowlby began to pioneer his work, linking patients' childhood stories to symptoms they presented. It appeared that children's behavior was affected by parental deprivation and the separations they experienced since childhood. He also made medical breakthroughs when he discovered that parents' childhood experiences also contribute significantly to the behavior of these emotionally disturbed children (Bretherton, 1994, p. 762). Although he initially established the theory on a child's attachment behavioral system, he attributed that each child has a distinct way of assessing responsiveness toward their primary caregivers and how they adjust their actions and behavior. behavior when responding to unfamiliar environments or threats. The studyThis report aims to discuss John Bowlby's research on attachment. The study focuses on infants and their primary caregivers, properly addressing the level of attachment between them and how they interact with each other. Through in-depth observations, this study will be able to determine how attachment affects the infant's sense of security and predetermines their future behavior. Methods Subjects or Participants: Bowlby studied infants aged 2 to 36 months. Although more research is needed from 37 months onwards, Bowlby believes that the following ages are the most crucial in the development of infants' behavioral characteristics. The researcher, however, did not mention other relevant factors regarding the participants such as their race, socio-economic level, etc. Strange Situation Procedure: To examine how attachments vary from situation to situation, Bowlby conducts... article ......t Theory: John Bowlby and Mary Ainsworth. A century of developmental psychology. American Psychological Association. Zeanah, C., Berlin, L. and Boris, N. (2011) Practitioner review: clinical applications of attachment theory and research for infants and young children. Journal of Child Psychology and Psychiatry. Blackwell Publishing. Main, M., Kaplan, N., & Cassidy, J. (1985). Attachment security in infancy, childhood and adulthood: a move to the level of representation. In I. Bretherton & E. Waters (Eds.), Growing Points in Attachment Theory and Research. Monographs of the Society for Research in Child Development. Kobak, R. and Madsen, S. (2008). Disturbances in attachment bonds: Implications for theory, research, and clinical intervention. In J. Cassidy & P. ​​R. Shaver (Eds.), Handbook of Attachment: Theory, research, and clinical applications (2nd edition).