In this Retrospective, we revisit our 2007 "College Composition and Communication" article in order to clarify our primary argument, address some questions and critiques that have arisen, and consider anew the value of composition courses that study writing. We review our core argument that engaging students with the research and ideas of writing studies, building declarative and procedural knowledge of writing, improves learning transfer. Now, using the example of Jan Meyer and Ray Land's notion of threshold concepts, we argue for the field to better name its knowledge and conceptions and to decide what portion is suitable for first-year students. We clarify the distinction between this broad underlying goal and our personal approaches to accomplishing it, emphasizing the diversity of approaches that have come to embody the study of writing in first-year composition. While maintaining that writing studies lacks recognition of itself as a field and of the value of its specialized knowledge to writing instruction, we revise our original argument to show how writing instructors from other fields and with other expertise can build familiarity with writing studies research without extensive, specialized study. Ultimately, we continue to advocate teaching our field's knowledge in first-year composition, while expanding our sense both of how to prepare instructors to do so and of the value of such teaching.