When selecting the spending categories for our compilation, we were guided by the definition of global public goods as institutions, mechanisms, and outcomes that provide quasi universal benefits, covering more than one group of countries, several population groups, and extending to both current and future generations (Kaul, Grunberg, and Stern, 1999). GPGs are non-rival and non-excludable: one country’s enjoyment of the good does not affect (or reduce) its enjoyment by others and once the good becomes available, no country can be excluded from sharing its benefits (Samuelson, 1954; Cornes and Sandler, 1986). For example, the IMF’s surveillance of global financial markets and members’ economies helps detect systemic risks and vulnerabilities early on in the global economy. The resulting early warning system encourages countries to take steps at home to reduce the risks of a global crisis.