Standard sources of data on international patenting suggest a surge in international patent activity in the last decade of the twentieth century. The World Intellectual Property Organization (WIPO) reports a five-fold increase in non-resident patent applications in Denmark and nearly a tripling in Germany, for example. During this period the European Patent Office (EPO) evolved to provide a simpler and cheaper means of seeking patent protection in most European countries. We find that some of the apparent explosion in patenting arises from an overstatement in the number of countries designated in European patents. Correcting for this mismeasurement, however, the data nevertheless imply substantial growth: 1) published European patent applications grew by nearly 6% annually between 1991 and 2000; 2) this growth was not at the expense of patents sought directly through national patent offices, which were small in number relative to European patents throughout the period; and 3) the number of destinations designated ...