Isotropic compression tests were performed on samples of unsaturated compacted kaolin in a modified triaxial cell that allowed separate control of pore water pressure and pore air pressure. Each test began with an equalization stage, during which the suction was reduced to a pre-selected value while maintaining the mean net stress constant. This was followed by a ramped consolidation stage, in which the mean net stress was increased at constant suction. The variation of specific volume during ramped consolidation showed clear evidence of a yield point and an elasto-plastic form of behaviour. The complex pattern of swelling and collapse observed during equalization was also explained by elastro-plastic behaviour and the existence of a yield curve in suction versus mean net stress space.