This is the first comprehensive description of the Circle of Security Intervention (COS). The book explains both theoretically and practically how to help parents better respond to the emotional needs of their children up to the age of five. The conceptual foundations of the COS are clearly articulated, and the innovative attachment-oriented assessment and intervention strategies are described in all clinical aspects. The Circle of Security is a proven, scientifically researched treatment program that has already been tested worldwide with children and parents facing attachment issues. The authors received the Bowlby-Ainsworth Award from the New York Attachment Consortium in 2013 for the development and implementation of the COS. Scientific engagement with the significance of attachment began in the 1980s.