Unsaturated soil mechanics represents a good deal of geotechnics practice worldwide, requiring refined analytical, testing and modelling methods. This book outlines experimental modelling of unsaturated silty sand, clayey silty sand, sandy silt, and silty clay, over a wide range of stress paths and modes of deformation, including suction controlled resonant column, bender element, biaxial (plane strain), triaxial (double-walled), true triaxial (cubical), and ring shear testing. It covers main testing procedures, key experimental results, and calibration protocols for constitutive modelling over a range of suction states (0- 300 MPa), using the axis-translation or vapour-pressure technique.