This Element is about the social dimensions of scientific knowledge. The first section asks in what ways scientific knowledge is social. The second section develops a conception of scientific knowledge that accommodates the insights of the first section, and is consonant with mainstream thinking about knowledge in analytic epistemology. The third section 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 section, and how to deal with scientific dissent. The fourth section reviews the ways epistemic and social elements mutually interact to coproduce scientific knowledge. This Element 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 Element focuses on themes and debates that date from the start of the second millennium.