In 1882, Robert Koch identified tuberculosis as an infectious bacterial disease. In the sixty years between this revelation and the discovery of an antibiotic treatment, streptomycin, the disease was widespread in Canada, often infecting children within their family homes. Soon, public concerns led to the establishment of hospitals that specialized in the treatment of tuberculosis, including the Toronto sanatorium, which opened in 1904 on the outskirts of the city. Situated in the era before streptomycin, Building Resistance explores children's diverse experiences with tuberculosis infection, disease, hospitalization, and treatment at the Toronto sanatorium between 1909 and 1950. This early sanatorium era was defined by the principles of resistance building, recognizing that the body itself possessed a potential to overcome tuberculosis through rest, nutrition, fresh air, and sometimes surgical intervention. Grounded in a rich and descriptive case study and based on archival research, the book holistically approaches the social and biological impact of infection and disease on the bodies, families, and lives of children. Lavishly illustrated, compassionate, and informative, Building Resistance details the inner dimensions and evolving treatment choices of an early modern hospital, as well as the fate of its young patients.