Recent progress has been made in systematic assessments of global biodiversity, such as the first Global Assessment on Biodiversity and Ecosystem Services from the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) released in spring 2018.  The purpose of these assessments is to understand the status of biodiversity and track changes over time.  However, this work overwhelmingly focuses on aboveground and aquatic ecosystems.  The Global Soil Biodiversity Initiative and partners are exploring opportunities to request a formal assessment of global soil biodiversity.  In this session, co-sponsored by the Soil Ecology Section, we lay the groundwork for such a proposal and seek input from ESA attendees to shape the project.  A series of speakers will share their taxonomic and ecological expertise to present an overview of soil biodiversity, emerging techniques for studying specific taxa, and ways to integrate data.  Open discussion with presenters and attendees will explore how to approach a global assessment of belowground diversity and how scientists can engage in the process.