Research on the relationship between contentious action and news production has often focused on the coverage and framing of specific events, not on the careers of keywords of the protest lexicon itself. However, these keywords play a central role in the negotiation of common understandings of social problems, the legitimation of claims and tactics, and even the shared imaginary of grassroots politics within communities of readers. This article seeks to contribute to this second avenue of media research by studying use of the concept activism and associated subject, activists. I ask how this word, which was a negative term for most of the twentieth century until the introduction and popularization of its modern sense in the 1960s, became a keyword of modern political participation by the public. A conceptual history grounded in insights of distributional semantics and semantic field theory, this article studies patterns of use of ‘activist’ and ‘activism’ in two major British quality newspapers, The Guardian and The Times. This comparative approach aims to identify both historical and media-internal factors that contributed to activism becoming a meaningful category in news reporting. Coverage is compared for three episodes of heightened civic contention: the student protests of 1967–1969; Eastern European human rights activism around the Helsinki Accords, 1975–1977; and the industrial strikes of the 1980s, particularly the period around the miner's strike, 1984–1986.