This text is a compendium of five decades of work relating to science, mechanics and improvement of highly expansive soil systems, application of improved methods to construction of stable civil engineering structures on such deposits. He has used a particulate approach incorporating thermodynamic properties of soil particles as matter to predict the behaviour of saturated expansive soil. The compiling of this massive work has been the effort of the co-authors. The behaviour of expansive soil deposits is found to be unconventional in nature. Prof. Katti has focused on the difference in behaviour by conducting identical studies on conventional soil systems. The book covers topics on basic property, swelling and swelling pressure measurements, shear strength behaviour under various conditions including depth effect, lateral earth pressure development under Ka, Ko and Kp conditions using large-scale devises, discovery of CNS technology and its field application, bearing capacity aspect with and without CNS and MSM, expansive soil improvement techniques, approach to design of rigid and flexible pavements, shallow and raft foundations; optimum length, Hd of underreamed piles, similarity between suction pressure measure approach and cohesion measure approach, use of conventional and small scale test data and simplified approach to estimate he and h, standards, and mechanics of expansive soil media and case histories. He has brought about limitations of existing conventional theories to deal with expansive soil behaviour and the need for incorporating thermodynamic parameters to predict behaviour of saturated expansive soils. This is a unique treatise covering the entire realm of behaviour of saturated expansive soil and control methods. It can act as a database for future research workers and scholars as a guide for construction for practicing engineers and as a sequentially organised scientifically based book for students.