This article is an introduction to “Holding Each Other in Mind: A Mentalization-based Approach to Dyadic Therapy,” which is a presentation of a clinical case. The paper presents a description of the child welfare agency in which the work took place and the Building Blocks project within the agency that designed the clinical program. Building Blocks is a program based on concepts of attachment and infant-caregiver communication patterns which offers dyadic mentalization-based treatment to parents and their children age 5 and under who are at risk or have already been reported to Child Protective Services. The program provides training in key concepts to agency therapists, who then provide dyadic treatment to caregivers and their young children. Therapists meet weekly for reflective supervision in alternating individual and group sessions. Parts of the treatment are videotaped, and the tapes are used to help parents understand their interactions with their children, to help therapists become more sensitive to adult-child communications, and to evaluate the efficacy of the program.