This chapter examines the conceptual and empirical contributions of attachment theory to the field of developmental psychopathology. It reviews the major elements and methods of attachment theory and research, and considers current evidence regarding a) the environmental and genetic determinants of attachment, b) short-and long-term continuity in attachment processes, c) the association between attachment and emerging psychopathology, d) candidate mediating mechanisms conveying risk, and d) the efficacy of attachment-focused interventions. We end with a consideration of the broader relevance of attachment theory for understanding the process and mechanisms of change in psychological therapies. We conclude that attachment represents a coherent and generally well-supported developmental construct, which is of great potential value as a framework for prevention and intervention. We also highlight several key outstanding issues and qualifications regarding the measurement of attachment, the scope and limits of its effects on children's outcomes, and unresolved scientific issues regarding causal mechanisms.