This case study explores the academic writing practices of some African American English-speaking high school students, focusing in particular on interactions of dialect and register. In some instances, students appear to draw from a range of dialect and register resources and to deploy them in hybridized forms in their compositions. One implication of this hybridity is that it suggests the need to include register analysis as part of linguistically informed approaches to writing instruction (i.e., approaches that apply variationist research and methods to educational settings). Additionally, this case study examines some of the reasons that motivate the production of hybridity, analyzing how the linguistic tasks in which students are asked to engage and students’ metalinguistic understandings play a role in the creation of hybridized texts. Finally, this study presents analytic methods that, while not new, are applied in a mixed way that attempts to systematically examine both dialect and register in texts.