After the great pandemic of 1348, the plague became endemic in Europe, affecting life at every level for more than three hundred years. In attempting to fight the dread enemy, the North Italian states had developed, by the early sixteenth century, a highly sophisticated system of public health. Special permanent magistracies combining legislative and executive powers were established to administer all public health matters. In this volume, Carlo M. Cipolla throws new light on the subject, utilizing newly uncovered and significant archival material. In the first essay, the author analyzes the complex set of interrelationships that existed between theory and practice in Renaissance epidemiology. The significance of this essay goes beyond the history of public health and extends to the larger history of science. In the second essay, Cipolla studies a case in which health matters became the object of intense diplomatic activity. In that instance, fully sovereign states envisaged interstate controls and relinquished discretionary powers for the sake of the "common health." Although the concerted effort was short-lived, it does represent an attempt at international health cooperation that was unmatched for another two centuries, until the first International Sanitary Conference, held in Paris in 1851. In the third essay, unusually detailed statistical documentation allows the author to analyze in detail the demographic, economic, and social aspects of the fight against the plague in a Tuscan city-Pistoia-during the epidemic of 1630-31. A richly documented appendix, forming an essay in itself, illustrates present knowledge of the clinical, pathological, and epidemiological features of the plague in the sixteenth and seventeenth centuries in Europe.