The use of reporting guidelines is an established yet still-evolving practice in the field of biomedicine. These documents are often linked to common methodologies (e.g., randomized clinical trials); they include multiple textual artifacts (e.g., checklists, flow diagrams) and have a history that is coextensive with the emergence and ongoing development of evidence-based medicine (e.g., as an epistemological orientation to research and decision making). Drawing on the concept of metagenre, this article examines how practitioners use reporting guidelines to define and regulate the boundaries of biomedical research and writing activity. The analysis, focusing on one prominent set of guidelines, shows how practitioners use the genre-metagenre dynamic to promote strategic intervention while upholding traditional principles and standards for evidence-based research and communication.