ABSTRACT The Science Service, established in 1921 by newspaper magnate, Edward Willis “E.W.” Scripps, and zoologist, William E. Ritter, was founded to educate the public about science. The overarching aims of the Service were to instill in the public a scientific habit of mind and improve the public’s critical thinking skills, thereby strengthening democracy. The Service acted as a liaison between scientists and the public by disseminating accessible scientific information through a variety of media, including The Science News-Letter. Service founders maintained that the agency would not promulgate propaganda “unless it be propaganda to urge the value of research and the usefulness of science.” Between the first and second world wars, the Service began an anti-propaganda campaign in its newsletter; cautioning readers about the dangers of propaganda, describing how to recognize propaganda, and explaining how to defend against it – providing the public with “psychological armor” in the words of Science Service writer, Marjorie Van de Water. Between 1926 and 1965, 187 newsletter articles included the keyword “propaganda.” This essay identifies, examines, and places in context, newsletter articles on propaganda and argues that, in spite of the organization’s stated mission, aspects of its counter-propaganda crusade veered into the realm of propaganda.