Dominant narratives of disciplinarity that WAC/WID confronts conflate disciplines with departments and material institutional structures, such as departments and professional organizations--what is here called "departmentality." The relative autonomy of disciplinarity from departmentality means that challenges to foundational concepts of disciplines are in fact normal to disciplinary work and do not threaten the material institutional structures associated with those disciplines, as illustrated by the history of challenges to foundational disciplinary concepts of basic writing and second language acquisition carried out in disciplinary writing. The relative autonomy of disciplinarity enables us to accept the legitimacy of the challenges translingual theory poses to conventional notions of language, identity, writing, and their relations to one another circulating in composition studies generally and second language writing in particular as contributions rather than threats to the disciplinary work of these areas of study.