This dissertation reveals how decreasing erectile function, aging and chronic illness shape older Mexican men's ideas and practices of masculinity. Based on ethnographic fieldwork in the Urology department of a government hospital in Cuernavaca, Mexico, it shows that despite post-Viagra global medicalization of erectile difficulty as the biomedical pathology erectile dysfunction (ED), participants generally rejected purely medical explanations of and treatments for decreasing erectile function, in favor of more complexly social accounts.

The first half of the dissertation discusses participants' understandings of masculinity, and provides the theoretical tools necessary to understand the relationships between changing ideas of manliness and erectile function. It introduces the "composite masculinities" analytic, based on insights from gender and science and technology studies, for studying the concrete mechanisms by which embodied changes in masculine selfhood occur in relationship to social, structural, and physical contexts. Using this approach, this section address participants' understandings of the relationship between "Mexicanness" and their own manhood, their shared expectation of shift from a sex-centered youthful masculinity to a 'mature" masculinity focused on home and family, and how relationships with women mediate men's performances of masculinity.

The second half examines interactions between bodily aging and illness, medical treatment, and participants' changing ways of being men. It situates decreasing erectile function in the epidemic of chronic illness sweeping Mexico, particularly type-2 diabetes, heart disease, and prostate problems. Describing the relationships between illness experience, social and structural context, and local understandings of health and illness, this section focuses on participants' relationships to medical erectile dysfunction (ED) treatment, explaining why most participants rejected ED treatment, and the experiences of the few who sought this treatment.

This research sheds new light on the understudied fields of masculinity and men's health, especially as one of the first works to focus on older, heterosexual men. It also provides a new analytic for understanding embodied changes in participants' gendered selves over time, which is applicable to studies of gender and selfhood more broadly. Finally, it counters stereotypes of Mexican masculinity as one-dimensionally "macho," and demonstrates that the seeming global hegemony of medical understandings of sexuality do not always obtain.