ArgumentThis article is based on a detailed survey of three British popular science magazines published during the interwar years. It focuses on the authors who wrote for the magazines, using the information to analyze the ways in which scientists and popular writers contributed to the dissemination of information about science and technology. It shows how the different readerships toward which the magazines were directed determined the proportion of trained scientists who provided material for publication. The most serious magazine,Discovery, featured almost exclusively material written by professional scientists, while the most popular,Armchair Science, favored writers who were not professional scientists, but who probably had some technical knowledge. Another magazine,Conquest, tried to provide a balance between authoritative and popular articles; however, it survived for only a few years.