This chapter interprets the scope and key definitions in Part II Marine Genetic Resource governance of the Biodiversity Beyond National Jurisdiction (BBNJ) Agreement. The purpose of this chapter is to: (a) aid practitioners and policy makers’ understanding of the rationale underlying the treaty obligations and key gaps in interpretation; (b) outline how scope and definitions shape the treaty framework and institutional arrangements; and (c) provide practical considerations for how scope and definitions might be implemented in practice by Parties. Through a textual analysis of the treaty and its evolution during preparatory and intergovernmental committee meetings, it critically analyzes scope in three dimensions: jurisdiction (geography, sovereignty and relationships with other instruments, frameworks and bodies); subject matter (physical materials, sequence information, traditional knowledge, activities and exclusions); and temporal scope (including retrospectivity). The chapter analyzes the principles of ‘without prejudice’, ‘non-appropriation’, ‘due diligence’ and ‘not undermining’ in the treaty context. It concludes that the BBNJ Agreement has an expansive scope requiring clarification and calibration by treaty bodies for a common approach to implementation by Parties.