Background: Attachment Science Introduction Attachment's Principals and Principles Attachment-informed Psychotherapy: Definition and Overview Affect Regulation in Attachment and Psychotherapy Sensitivity, Mirroring, and Play: Foundations of Attachment Security in Caregivers and Therapists The Neuroscience of Parental Sensitivity Mentalising 'Earned Security': Attachment and Resilience 'Organised Insecurity': Fostering Security through Therapeutic Conversations 'Disorganised Insecurity': Attachment Approaches to Complex Disorders From Stasis to Movement: An Attachment Model of Psychotherapeutic Change The Improbable Profession: An Attachment-Bayesian Model of Psychodynamic Change Attachment, Mentalising, and Child Psychotherapy: Working with Parents Attachment in Couples and Families Attachment and Society Epilogue Selected Attachment Bibliography References