In recent decades we have witnessed an exponential increase in the number of studies highlighting the importance of conserving soil biodiversity to maintain soil functions, as well as the health of terrestrial ecosystems as a whole. It is evident that soil biodiversity plays a key role in the resilience and mitigation capacity of terrestrial systems, and it seems increasingly clear that we cannot predict the response of terrestrial ecosystems without considering soil biodiversity as an important asset to take into account. However, there is still a strong bias towards soil microorganisms in the study of soil biodiversity, partly because the advance of massive sequencing tools has made the study of soil microbial communities much easier. Much less attention has been being paid to the role of soil fauna, mainly invertebrates (e.g. myriapods, insects, arachnids, oligochaetes), which are highly abundant and diverse in soil, but whose functional role in soil is being systematically underestimated, partly because inventorying soil invertebrate biodiversity is methodologically challenging. This can be a problem when interpreting and evaluating the current and future vulnerability and resilience of soils to the challenges they face (climate change, providing raw materials for a growing world population). However, we know that soil fauna plays a fundamental role in key functions such as soil carbon sequestration or maintaining the soil physical properties that allow plants to access soil water and nutrient resources. Therefore, in this session we want to welcome summaries of studies (e.g. experimental, methodological, field monitoring or modeling) that attempt to address this knowledge gap with a focus on improving our understanding of the role of soil fauna in the functioning of soils and terrestrial ecosystems.