This Pivot book provides a framework for understanding the economic and potentially unequal effects of pandemics, focusing closely on the Spanish Flu. It provides an in-depth analysis of the different effects of the Spanish Flu on the economy from unequal mortality to wages, housing and output. There is a general review of the literature but an important feature of this book is that it explains results using data from Spain, an ideal country to perform this exercise, as its mortality data is not affected by the First World War. Spain was also developed enough to have reliable data, but it was very heterogeneous across regions which will allow a comparison of more and less developed regions. No other book exists that offers a comprehensive and data-driven view of the effects of the Spanish Flu, which is the closest pandemic example to Covid-19.  With the outbreak of Covid-19 increasing the need to learn about the economic effects of pandemics, this book will be of interest to academics and students of economic history, macroeconomics (economic crises) and economic development, as well being accessible for the general reader.