How can social change become possible when secondary teachers approach argument as participation in ongoing conversations? The authors illustrate how--through writing, speaking, and reading to develop a letter to their principal arguing for a school policy change--secondary students participated in multiple conversational spheres across time and place. Although neither collaborative "letter writing to the principal" tasks nor "argument as conversation" stances are new, the approach presented is novel in its commitment to braiding oral and written language together within the framework of argument as conversation. This approach contrasts to more common practices of seeing conversation as preparation for writing. This approach is valuable not only for fostering students' learning about processes, structures, and technical skills of argumentative writing but also, and more importantly, for experiencing what it feels like to become empowered disputants who affect social change in response to ongoing conversations that matter to students.