As this article argues, a systematic approach to WAC/WID work that conceptualizes interdisciplinary interaction as a deliberative argument (rather than a benign collaboration) benefits all aspects of a WAC/WID program, in particular projects involving writing and other disciplinary faculty. Our approach builds from scholarship that highlights the distinction between “adversarial” and “collaborative” deliberation, in particular the work of Patricia Roberts-Miller and the foundational rhetoric theories of Chaïm Perelman and Lucie Olbrechts-Tyteca. After laying out the contours of our approach, the article details a recent not-quite-successful attempt at interdisciplinary collaboration. In documenting this example, we illustrate that a systematic focus on combining adversarial and collaborative deliberation can prevent common pitfalls of writing scholars working with other disciplinary faculty, including the problems that arise when writing is considered ancillary to disciplinary “content.” In this sense, our example highlights the deliberative missteps that our approach is precisely designed to prevent.