Book excerpt: A transnational approach to understanding and analyzing knowledge circulation. Focusing on what happens to knowledge at national borders, rather than treating it as flowing like currents across them, or diffusing out from center to periphery, the contributors to this collection stress the human intervention that shapes and drives how knowledge is processed, mobilized, and repurposed in transnational transactions to serve differing and uneven 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 vast range of platforms and objects of knowledge, from tangible commodities--like hybrid wheat seeds, penicillin, Robusta coffee, naval weaponry, and high-performance computers--to the more conceptual apparatuses of telecommunications, statistics, and food sovereignty. 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, and Palestine and the West Bank, as well as the United States and United Kingdom. The variety of the kinds of knowledge addressed in the chapters brings forth an extraordinary array of state and non-state actors and institutions committed to performing the work needed to move knowledge across national borders.