The fluxes and partitioning of carbon, nutrients and water in environmental systems are central components of ecosystem functioning. They are also subject to intensive scientific investigation across many research fields of the BayCEER. Here, stable isotope technologies offer an unparalleled handle to track matter fluxes, allocation and organismic involvement, either at natural isotope abundance or as enriched amendments. Across a wide range of (bio)markers, analytical technologies and research disciplines, this session aims to showcase ongoing research involving stable isotope technologies at the BayCEER. We aim to provide a nucleus for stimulating scientific discussion on the latest advances in the use of stable isotope strategies to improve our understanding of ecosystem functioning.