The paradigm of content area literacy instruction is shifting from a view of literacy as generalizable across the curriculum to a disciplinary perspective of literacies specific to the specialized language, text structures, and habits of thinking within particular subject areas. Preservice STEM (science, technology, engineering, and mathematics) teachers must be knowledgeable in their content fields and possess competence in pedagogical practices that allow them to scaffold their students' literacy growth within these disciplines. This study examined how infusing a disciplinary literacy project into a content area literacy course affected preservice secondary science and mathematics teachers' disciplinary literacy pedagogy and practice. The findings of this study suggest that structured inquiry into disciplinary communities enhances preservice teachers' understanding of disciplinary literacy development, but this knowledge is not easily transferred into classroom instruction. Implications for future research on disciplinary literacy models and preservice teacher preparation are discussed.