Until a few decades ago, student writing stood as a distant third in the three R's. Since the late 1970s, however, students have been asked to write more, and teachers have been expected to teach writing more specifically. In spite of this mandate, however, little has been done to prepare teachers for this shift in the curriculum. This primer provides a brief history of the field, as well as an exploration of what we now know about teaching. Teachers entering the field as well as seasoned veterans will find how to foster student writers, and to grow as writers themselves.