All central banks manage the supply of money and credit in their countries, increasing and decreasing them as needed to provide what economies need to keep growing. The way central banks typically handle that job involves short-term interest rates. But when inflation is low, central banks can't use their usual methods to get money and credit into an economy that needs it. Several essays in this volume describe the work of economists who have investigated problems that central banks might have when inflation gets low. Other essays investigate related questions such as whether an economy suffers when it moves from high inflation to low inflation, what the costs of inflation are to economic welfare, and whether a little bit of inflation can actually be good for economic growth.