The contributors to this collection focus on what happens to knowledge and know-how at national borders. Rather than treating it as flowing like currents across them, or diffusing out from center to periphery, they stress the human intervention that shapes how knowledge is processed, mobilized, and repurposed in transnational transactions to serve diverse interests, constraints, and environments. The chapters consider both what knowledge travels and how it travels across borders of varying permeability that impede or facilitate its movement. They look closely at a variety of platforms and objects of knowledge, from tangible commodities-like hybrid wheat seeds, penicillin, Robusta coffee, naval weaponry, seed banks, satellites and high-performance computers-to the more conceptual apparatuses of plant phenotype data and statistics. Moreover, this volume decenters the Global North, tracking how knowledge moves along multiple paths across the borders of Mexico, India, Portugal, Guinea-Bissau, the Soviet Union, China, Angola, Palestine and the West Bank, as well as the United States and the United Kingdom. An important new work of transnational history, this collection recasts the way we understand and analyze knowledge circulation.