In recent years, a number of authors have shown that, if by sustainable development we are to mean that welfare across the generations should not decline over time, the index that measures an economy's productive base should be an inclusive measure of wealth. The authors of IWR 2018 follow that line of thought and extend the empirical reach of IWR 2012 and IWR 2014. They develop the idea of inclusive wealth, uncover the logic underlying its use in sustainability analysis, and then put it to work in tracking the inclusive wealth of nations.