The first scientific journal was established in the 17th century. Over the last 140 years, science writing has developed along two clear lines targeting specialist and non-specialist audiences. In the 19th century, specialist publications Nature and Science and new periodicals targeting the non-specialist student of science Popular Science and Scientific American were founded. Now, in the first decades of the 21st century, writing in specialized scientific journals has become highly technical and often inaccessible to anyone outside of the field. The profession of popular science writing has also become more vital than ever as writers attempt to translate the important messages in scientific findings to a common language that the public, which funds most science research in the U.S., can understand. Identifying and understanding the development of key differences in style and genre between 21st century specialist and non-specialist writing is necessary for bridging the gap between science and the public. Additionally, tracking the genre’s evolution over time reveals the key similarities and differences in the authors’ purposes, audiences’ expectations, and conventions of the science journal article as a whole. To accomplish these goals, I present a genre and style analysis of science writing from three key periods of time: the 17th century, the late 19th century, and the early 21st century. For the decades of the 19th and 21st centuries, I analyze selected articles to compare features in selected specialist (Nature, Science) and non-specialist (Popular Science, Scientific American) journal articles.