We propose that the global spread of ideas affects international economic openness policies, and that to omit ideology as an explanatory variable for economic globalization is to risk omitted variable bias. Using voting data, we create measures of global ideology regarding economic openness and propose that changes in both global and domestic ideology influence how open or closed to international finance an economy is. We also test other influences on liberalization, including proposed state-centered diffusion mechanisms. Using PCSTS and system-GMM models, we estimate the determinants of change in international capital account regulation for 82 countries, 1955 to 1999. We thereby examine diffusion of both liberalizations (1950s and 1990s) and closures (1960s and 1970s). Changes in both global and domestic ideology robustly influence liberalization and closure. The capital account policies of neighboring countries (positively) and of the leading economies (negatively) also influenced a country's capital account liberalization.