Despite its proliferation in technology studies, the concept of “path dependence” has scarcely been applied to epistemology. In this essay, I investigate path dependence in the production of scientific knowledge, first, by considering Kuhn's scattered remarks that lend support to a path-dependence thesis (Section I) and second by developing and criticising Kuhn's embryonic account (Sections II and III). I examine a case from high-energy physics that brings the path-dependent nature of scientific knowledge to the fore and I pay attention to (...) two sources of path dependence—“theoretical” and “instrumental”. The latter source is particularly important in “big science”. I ask in Section IV whether path dependence in scientific knowledge can lead to circumstances like those in the technological field, in which a theory can come to dominate a scientific speciality even though it is inferior to alternatives. In Section V, I ask what implications my thesis has for science policy. (shrink)