This book studies the interactions between monetary and fiscal policies in the euro area. It carefully discusses the process of policy competition and the structure of policy cooperation. As to policy competition, the focus is on competition between the European central bank, the American central bank, the German government, and the French government. As to policy cooperation, the focus is on the same institutions. These are higher-dimensional issues. The policy targets are price stability and full employment. The policy makers follow cold-turkey or gradualist strategies. The policy decisions are taken sequentially or simultaneously. Monetary and fiscal policies have spillover effects. Special features of this book are numerical simulations of policy competition and numerical solutions to policy cooperation.