This paper aims to identify the core assumptions of the control-mastery theory (CMT) – those assumptions whose falsification would determine the abandonment of the theory itself. These concepts are the adaptive nature of basic human motivations; the sophisticated and adaptive nature of unconscious mental functioning; the overarching role of safety in the regulation of conscious and unconscious mental functioning; the prosocial nature of certain basic human motivations; the centrality of beliefs for understanding how human beings relate to reality and other human beings; and the ontological unity of the human Self. We show how the application of these assumptions to clinical phenomena that apparently contradict them has given rise to the more innovative concepts of the CMT – such as the concept of patients’ tests, coaches, and plans – and has emphasized the centrality of guilt and shame in psychopathology. In contrast to the core concepts delineated above, modifying these derived concepts would not imply modifying the entire theory. Finally, we show how these concepts shape the clinical work of therapists who embrace the CMT.