Science journalism is a specialized genre of communicating science, adhering to more or less formalized practices of journalism and often (but not always) reporting science as news. By the turn of the 19th century, various forms of science writing, including science writing for newsprint and popular magazines, were well established. With the institutionalisation of modern journalism in the course of the late 19th and early 20th century, including professional societies, schools of journalism and the rise of mass media, some science writers began contemplating a new professional identity as science journalists and a new genre of science writing, namely science journalism.

This paper traces the evolution of science journalism in the course of 20th century. Seeing science journalists as quintessential boundary workers who are charged with reporting science on the boundary between science and the public, the paper identifies three ideal genres or repertoires for science journalists: “science news”, selecting events in science that conform to (more or less explicit) norms of news journalism; “science advocacy”, promoting the value of science to the public; and “fourth estate science journalism”, critically investigating the role of science in society. The three genres of science journalism each assign a different role to the science journalist on the boundary between science and the public, but also have implications for the rhetorical and narratives codes of science. Looking at a few selected case studies from United Kingdom, Germany, and Denmark from the early to the late 20th century, it will be argued that there is no simple historical progression from one genre to another. Rather, the three genres enable, but also constrain the ways in which scientific knowledge travels from the domain of scientific communication to the realm of public discourse.