John Bowlby revolutionized the view of mother-infant bonds and relationships when he outlined attachment theory. This article reviews attachment theory and how history and research impact clinical practice. Attachment definitions and components are offered, some research history is highlighted and critiqued, new areas of research are indicated from globalization and marginalization perspectives, and implications for social work treatment with children are discussed including differentiation and integration of the self, attachment reparation, and reinforcement of internal working models. Attachment theory premises are based in an enduring pattern of relatedness that exists, not only for survival, but also for connection.