Nathan Shock, the leader of the NIH's gerontology program from 1941 to 1976, played a pivotal role in creating the science of aging as a research field in America. By illustrating his works, I explore the complexity surrounding the term, the "biomedicalization of aging," a subject studied recently by several scholars including Tiago Moreira and Paolo Palladino. Indeed, "biomedicalization" is understood in many different ways. Whereas it was often equated to molecular reductionism, Peter Keating, Albert Cambrosio, Adele Clarke, and Ilana Löwy have shown that biomedicalization involves a set of more complex changes in laboratories, clinics, and patients' social worlds with a deep cultural repercussion. According to them, modern biomedicine, while stressing the detailed identification of diseases in the laboratory, has complex relations with patients' activism, the blurring boundary between laboratories and clinics, and the neoliberal commercial interest. Focusing on aging and gerontology as the subject, my paper shows the complexity and inconsistency related to biomedicalization. I first will discuss how Shock tried to find the physiological and biochemical mechanism of aging using model organisms, biomolecules, and senior patients in the Baltimore City Hospitals. Then I illuminate how this work was placed in a broader social context associated with the elderly's continued social participation, job security, and health management. This explains, I claim, his unique choice of publishable results, his refusal to cooperate with the American Geriatrics Society, and psychologist James Birren's creation of a separate section of gerontology in the NIH after being disillusioned by Shock's "heavy biomedical orientation."