While most soil biodiversity studies focus on surface horizons, EU project DeepHorizon extends sampling to depths of up to 2 meters to better understand how below-ground communities contribute to long-term ecosystem stability and nutrient cycling. Within this framework, the present component aims to quantify mesofauna diversity across soil depth, country, and land use, with particular emphasis on Acari (mites) and Collembola (springtails) and earthworms. It was hypothesized that (i) surface soils support greater abundance and diversity than deeper horizons, (ii) community composition shifts systematically with depth due to environmental filtering, and (iii) land use modulates these vertical patterns. Soil samples collected across multiple European countries and grassland, cropland and forest land-use systems were processed using Tullgren funnels over a five-day extraction period. Specimens were identified under a stereo microscope to order or family level. Preliminary analyses indicate that surface soils (0–10 cm) support significantly higher abundance, taxonomic richness, and diversity than deeper layers. Non-metric multidimensional scaling (NMDS; stress = 0.05) reveals a clear compositional gradient with depth, with shallow samples exhibiting greater heterogeneity and deeper horizons forming tightly clustered assemblages. PERMANOVA confirms significant effects of country, land use, and soil depth, including their interactions (p = 0.001). Indicator species analysis identified Parasitidae (Mesostigmata) as significantly associated with grassland systems. Deeper layers were dominated by a single taxonomic group and increasingly characterised by Sarcoptiformes dominance, consistent with stress-tolerant Oribatid assemblages in resource- limited depths. These preliminary findings suggest strong vertical environmental filtering and reduced structural complexity with increasing depth. Ongoing work will refine taxonomic resolution and integrate functional metrics to better understand how subsoil mesofauna contribute to ecosystem resilience under different land- use systems.