The creation of nation-states in Europe has generally been assumed to be intrinsic to modernization and to be irreversible. The disintegration of Czechoslovakia, the Soviet Union, and Yugoslavia demonstrates that the process is not irreversible. I argue that in the case of Yugoslavia, (1) disintegration was caused by the interaction between domestic policies with regard to nationalities and integration into the global economy and (2) the impact of the disintegration of the federation on health care and public health systems has been profound. Improving and converging measures of mortality before the collapse gave way to increasing disparities afterward. The lesson is that processes of individual and social modernization do not result in improvements in health and well-being that are necessarily irreversible or shared equally.