Capital moves more rapidly across national borders now than it has in at least fifty years and perhaps in history. This article examines the effects of capital mobility on different groups in national societies and on the politics of economic policymaking. It begins by emphasizing that while financial markets are highly integrated within the developed world, many investments are still quite specific with respect to firm, sector, or location. It then argues that contemporary levels of international capital mobility have a differential impact on socioeconomic groups. Over the long run, increased capital mobility tends to favor owners of capital over other groups. In the shorter run, owners and workers in specific sectors in capital-exporting countries bear much of the burden of adjusting to increased capital mobility. These patterns can be expected to lead to political divisions about whether or not to encourage or increase international capital market integration. The article then demonstrates that capital mobility also affects the politics of other economic policies. Most centrally, it shifts debate toward the exchange rate as an intermediate or ultimate policy instrument. In this context, it tends to pit groups that favor exchange rate stability against groups that are more concerned about national monetary policy autonomy and therefore less concerned about exchange rate stability. Similarly, it tends to drive a wedge between groups that favor an appreciated exchange rate and groups that favor a depreciated one. These divisions have important implications for such economic policies as European monetary and currency union, the dollar-yen exchange rate, and international macroeconomic policy coordination.