Standards have become one of the most important nontariff barriers to trade, especially national product standards that specify design or performance characteristics of manufactured goods. Divergent national standards often inhibit trade, whereas regional and international standards increasingly serve as instruments of trade liberalization. Consequently, the setting of international standards—seemingly technical and apolitical—is rapidly becoming an issue of economic and political salience. But who sets international standards? Who wins, who loses? This article offers a fresh analytical approach to the study of international standards, which the authors call the institutional complementarities approach. It builds on insights from realism and the “Battle of the Sexes” coordination game but emphasizes complementarities of historically conditioned standardization systems at the national level with the institutional structure of standardization at the international level. It posits that, after controlling for other factors that influence involvement in international standardization, differences in institutional complementarities play a critical though largely accidental role in placing firms from different countries or regions in a first- or second-mover position when standardization becomes global. The authors illustrate the insightfulness of this approach through statistical analyses of the first scientific set of data on standards use and standardization, collected by the authors through an international online survey.