This Elements is about the social dimensions of scientific knowledge. The first chapter asks in what ways scientific knowledge is social. The second chapter develops a conception of scientific knowledge that accommodates the insights of the first chapter, and is consonant with mainstream thinking about knowledge in analytic epistemology. The third chapter asks under what conditions we can tell, in the real world, that a consensus in a scientific community amounts to shared scientific knowledge, as characterized in the second chapter, and how to deal with scientific dissent. The forth chapter reviews the ways epistemic and social elements mutually interact to coproduce scientific knowledge. This Elements engages with literature from philosophy of science and social epistemology, especially social epistemology of science, as well as Science, Technology, and Society (STS), and analytic epistemology. The book focuses on themes and debates since the start of the second millennium.