"The social system of knowledge—or knowledge system, for short—is an accounting scheme that helps organize the search for social impact of science (SIS) indicators. The accounting scheme specifies six related knowledge functions (production, structuring, storage, distribution, utilization, and mandating) that are performed in different domains (industry, agriculture, education, and so forth) by many institutions and organizations that vary in size, autonomy, specialization, and complexity. By mediating relations between science and society, these institutions and organizations facilitate and retard the impact of science on the larger society. The knowledge systems accounting scheme also helps identify aspects of science impacts on society (e.g., scientific evidence), aspects of society on which science impacts (e.g., the economy, polity, and culture), and structures by which social impacts of science are mediated (e.g., technical communities). The knowledge system provides a conceptual base for the future development of what has been called “knowledge systems accounting” (see Dunn and Holzner, this volume)."