Recent high-risk longitudinal studies have documented a unique contribution of the quality of the early mother–child relationship to diverse forms of psychopathology in young adulthood, even with family economic status, later traumatic experiences, and some genetic factors controlled. In addition, measures of attachment-related deviations in caregiver–infant interaction predict more than measures of infant attachment behavior alone. This article reviews those findings in the context of cross-disciplinary thinking on the importance of shared subjectivities in human evolution and development and in the context of recent studies beginning to map the intersection between processes of interaction and the development of the child's propensities to share mental states with others