Reading is fundamental to science and not an adjunct to its practice. In other words, understanding the meaning of the various forms of written discourse employed in the creation, discussion, and communication of scientific knowledge is inherent to how science works. The language used in science, however, sets up a barrier, that in order to be overcome requires all students to have a clear understanding of the features of the multimodal informational texts employed in science and the strategies they can use to decode the scientific concepts communicated in informational texts. We argue that all teachers of science must develop a functional understanding of reading comprehension as part of their professional knowledge and skill. After describing our rationale for including knowledge about reading as a professional knowledge base every teacher of science should have, we outline the knowledge about language teachers must develop, the knowledge about the challenges that reading comprehension of science texts poses for students, and the knowledge about instructional strategies science teachers should know to support their students' reading comprehension of science texts. Implications regarding the essential role that knowledge about reading should play in the preparation of science teachers are also discussed here.