The flow of knowledge through trade in services represents the convergence of two recent trends in U.S. industrial science and technology (SandT): an increase in RandD performance in the service sector and an increase in external and overseas innovation linkages. RandD-related data on affiliated trade in international services represent a new indicator of international industrial knowledge and technology flows. Other such indicators include high-technology goods trade, patent royalties and license fees, and foreign direct investment. International trade in research, development, and testing (RDT) services is contributing to the U.S. trade surplus in business services overall, according to data from the Bureau of Economic Analysis (BEA). Trade in RDT services can be separated into its component parts: affiliated (intracompany) and unaffiliated (cross-company) trade. Newly available data on affiliated trade show that since at least 2001, U.S. trade surpluses in RDT services have been driven more by U.S. affiliates of foreign multinational corporations (MNCs) and their relatively large exports of services than by parent companies of U.S. MNCs. This finding is consistent with the growing share these affiliates have in U.S. industrial RandD. In contrast, the unaffiliated trade surplus in RDT services has been down since 2010, due to the faster growth in imports than in exports of these services.