This chapter is about the interplay between psychiatry, general practitioners, and other specialists. First, the development of consultation-liaison psychiatry (CLP) from European psychosomatic tradition to its establishment in the United States is reviewed. CLP is a subspecialty of psychiatry and a way to organize mental health care in the general hospital, as well as to promote the interplay between hospital and territorial facilities, the latter including primary care services. Second, emphasis is given to CLP as forma mentis, which goes beyond the concept of psychiatric subspecialty. In this perspective, CLP is conceived as a role that each psychiatrist can play while working in different areas of mental health care, as well as at the interface with non-psychiatric departments. Work organization in mental health care represents a crossroad between the two conceptions of CLP here dealt with (i.e., subspecialty and forma mentis). To provide an example, we refer to the empirical context represented by the organizational model named “Mental Health Department” (MHD), developed in Italy in the 1970s to deliver mental health care. We chose this model for several reasons, including that Italy was the first country to close asylums, with a process that started in 1978 and ended in 1999. Yet, new challenges faced by psychiatry in the last years suggest the need for innovation. This topic is addressed by building on the knowledge of Industry 4.0 and the Fourth Industrial Revolution. We discuss the model of MHD 4.0, which may help cope with the crisis of the national health services, the lack of health professionals, the increasing age of the population, and the reduction of income and economic growth experienced by several countries. A measure of the capability of CLP to impact economic resources destinated to health care is provided. Also, implications of CLP for psychiatric training are discussed, with reference to general and specific skills that trainees may acquire during their internship in CLP settings, thanks to collaboration with senior psychiatrists and generational transmission of skills from the latter. Once acquired, such skills may be implemented in psychiatric settings other than general hospitals.