The Black Death, a pandemic caused by the bacterium Yersinia pestis, arrived in England in 1348 and killed more than a third of the population in less than two years. It struck a population that was experiencing the negative effects of overpopulation and that had already collectively suffered through several severe famines resulting from dramatic climate changes associated with the end of the Medieval Climate Anomaly. The pre-Black Death period was also characterized by widening social disparities that might have made the population vulnerable to disaster. At the same time as these country-wide crises, the city of London was undergoing rapid increases in population size and density. This chapter summarizes bioarchaeological research that has been done using several medieval cemeteries from London to explore the effects of climate change, social inequality, and urbanization on general levels of health within the city. The results of skeletal analyses, when combined with existing historical information, indicate that health, in general, declined before the Black Death; the effects of the Black Death may have been worsened by these declines in health. Examination of the context of the Black Death might reveal similar conditions in living urban populations that can be modified to mitigate the effects of future disasters.