This session will once again bring together biogeochemists, ecologists, and paleoclimatologists analyzing stable isotopes of organic molecules to track biochemical, ecohydrological, and ecophysiological processes in biotic (plants, microbes, fungi, and algae, a.o.) and abiotic (soil, sediment, water, and aerosol) samples across different scales. We particularly encourage people to present new compound-specific methods and applications giving original and valuable biological information in both modern and biogeological contexts. We appreciate contributions on new mass (GC, LC, laser ablation) and laser spectrometer methods (gases, smaller molecules, VOCs), as well as NMR and clumped isotopes techniques. This session will offer an overview of what proxies are available and what information can be extracted from them. This session will also provide an opportunity for method and proxy developers to present their new tools to those eager to use them in studies investigating different biological processes (e.g. element allocations, responses to environmental and hydrological changes, and ecosystem functioning). We aim for an interdisciplinary dialogue that will procure new insights into the current and the next-generation of cutting-edge techniques to study the Earth system.