Developing academic literacy involves learning valued content and rhetoric in a discipline. Within history, writing from primary documents to construct an evidenced interpretation of an issue requires students to transform both background and document knowledge, read and interpret historical documents, and manage discourse synthesis. The authors examine the potential of the Advanced Placement Document-Based Question as constructed and presented by an exemplary teacher to engage students in historical reasoning and writing. The authors analyzed how five students responded to four document-based questions over a year, tracing how organization, document use, and citation language indicate the degree to which writers transformed and integrated information in disciplinary ways. Students moved from knowledge telling (listing period and document content as discrete information bits) to knowledge transformation (integrating content as interpreted evidence for an argument). Students had difficulty learning to handle the complex layers of the task. The authors discuss how instruction might mediate this complexity and promote academic literacy.