Fire affects entire ecosystems – their flora, fauna, the atmosphere and soil. Research on the effects of fire to date has focussed primarily on the former three, whereas effects on the soil system have seen less attention. Burning and resulting post-fire environmental conditions can alter the functioning of soils physically (e.g. aggregate stability, pore size, distribution, water repellency and runoff response), chemically (e.g. nutrient availability, mineralogy, pH and C : N ratios) and biologically (e.g. biomass productivity, microbial composition and carbon sequestration). These fire-induced alterations have typically been examined in isolation by researchers in separate disciplines despite the sometimes strong relationship between some of these physical, chemical and biological effects. This special issue brings together studies from diverse disciplines, focussing on a wide spectrum of fire effects on the soil system. Here we aim to summarise, evaluate and set into context some of the new insights arising from these studies. A case is made for enhanced cross-disciplinary collaboration and the use of multi-scale research approaches in order to meet existing and future research challenges in this diverse field.