Volcanic soils are widely encountered around the world and they underlay several cities, making an understanding of their geotechnical properties of great importance, particularly since the same geological processes responsible for their deposition also generate earthquakes. Landslides in volcanic soils, often of catastrophic proportions, are frequently triggered both by seismic ground shaking and by heavy rainfall. Despite the wide occurrence of these soils and the hazards associated with their tendency to become highly unstable during earthquakes and heavy precipitation, there are relatively few published studies on their geotechnical characterisation, much less attempts to identify common properties and formulate a generic model for their behaviour. Studies of volcanic soils in a few locations around the world are briefly reviewed, prior to the presentation of some results of testing programmes on volcanic soil samples from Central America and exploratory slope stability analyses.