In 1936, the servicio médico-social (SMS) was established by the Universidad Nacional Autónoma de México (UNAM) and the Departamento de Salubridad Pública (DSP) of President Lázaro Cárdenas del Río (1934-1940). The SMS was a public health/medical education program that would require sixth-year medical students at the UNAM to spend a period of approximately six months doing medical service, basic sanitary oversight, and record-taking in a rural Mexican village, industrial site, or workcamp. It was a low-cost, low-footprint program that permitted Mexico to address problems of health infrastructure in an efficient manner. While scholars to date have seen the SMS as a reflection of the powerful institutional expansion of the post-Revolutionary Mexican State under President Cárdenas in the domain of health, in this dissertation, I take an alternative approach. I argue that the SMS reflected not a rigid clinico-politics resting upon the monolithic, domineering power of the State, but rather, that the SMS reflected a multifaceted, negotiated, open politics of health that rested upon a foundation of emotion. Drawing upon the work of historian of emotions William Reddy, I argue that the SMS was product of the navigation of feeling, and inspired medical students to their own navigation of feeling. It cemented a détente between the Cardenista State, impatient with Medicine’s cold and disinterested emotional regime, and the profession of Medicine, concerned with the preservation of its autonomy. The program would “socialize” students, in the argot of the time, catalyzing within them feelings of compassion for vulnerable Mexican citizens, thus reorienting Medicine to be more in line with the priorities of Cardenistas. Students were not passive objects in this emotional conflict. They were key actors who determined the ultimate form the politics of health took in Mexico’s localities. It was by their performances of compassion, their navigation of feeling—in receptional theses submitted to the UNAM, and in clinical service described in them—that students participated in Cardenista politics. Compassion served as a matrix within which students could transform Cardenista ideals for Mexican nation—modernization, national capitalism, eugenics, hygienization—into the concrete political action of clinical care. In this way, this dissertation not only enhances our understanding of the emotional dimensions of Cardenismo’s politics. It also shows that the practice of Medicine involves the careful cultivation of feeling.