Patients with functional somatic disorders (FSD) are markedly heterogeneous with regard to the factors contributing to their illness, their symptoms, and treatment response. In this article, we present a contemporary psychodynamic approach to the conceptualization and treatment of these patients based on attachment and mentalization theory. Extant research is reviewed that suggests a key role for attachment history and mentalization in determining stress and affect regulation, and immune and pain-regulating systems. We focus more specifically on the high interpersonal and metabolic costs associated with the excessive use of insecure secondary attachment strategies in response to stress, and the associated impairments in (embodied) mentalization in patients, both as a cause and consequence of FSD. Finally, a new brief psychodynamic intervention for patients with functional somatic complaints is discussed.