From the 1970s to the 2010s, the natural rate of interest in the US and other advanced economies fell. In the last decade, it has started to rise, and it has further to climb. That change reflects seismic shifts in demographics, technology, and geopolitics. In the future, risks from war to artificial intelligence and climate change could accelerate the rise. The Price of Money explains the evolution of the natural rate, the forces driving it, where it is headed, and what that means for everyone from Wall Street titans to 401K investors.