Permeability is a fundamental physical property governing the efficacy and rates of many geological processes. Our ability to measure or characterise the values and distributions of permeability attending geological processes at a range of scales is critical to many facets of geoscience (e.g., volcanology, structural geology, geothermal energy, geotechnical engineering, and petroleum geoscience). Technological advances facilitate ever-more detailed descriptions of permeability and yet critical challenges remain, for example: Understanding the evolution (e.g., creation or destruction) of permeability in volcanic conduits and edifices that control degassing rates; the extent of permeability evolution as a function of time/ strain/ stress in fault zones; the influence of temperature, large or fluctuating pressure gradients and destructive pore fluids on the longevity of resource exploitation; and the importance of scale-variance of permeability across all geological settings. For these reasons, considerable effort across the field of geoscience is focussed on understanding and quantifying permeability through combined field, laboratory, and modelling studies. Here, we invite field-, experimental-, technical-, theoretical- and model-based studies that discuss or tackle permeability development, constraint or evolution. Our intent is to foster strong interactions between research groups by soliciting contributions from diverse subdisciplines including (but not limited to) volcanology, rock and magma mechanics and physics, sedimentology, petrology, structural geology, and geophysics.