The rapid development of Mexico's national health administration throughout the 1920s and 1930s owed much of its success to the Rockefeller Foundation's public health initiatives. Resulting advancements included disease eradication, sanitation campaigns, and health education programs. However, by the 1940s, these projects remained understaffed, underfunded, and therefore underdeveloped. Correspondence by Rockefeller officers reveals their perpetual frustration with inadequate library and laboratory resources, lack of personnel supervision, insufficient space, inconsistency in medical education, scarcity of well-trained health officials, ineffective health networks and administration, and difficulties with acceptance in the local communities. My research explores the domestic and international obstacles to establishing a well-developed public health initiative in Mexico during the 1940s and 1950s and will offer new insight into the limitations of international health campaigns by the Rockefeller Foundation.