This work reviews soil mechanics in the light of critical state soil mechanics, developed at the University of Cambridge, England in the late 1960s. Critical state concepts gained widespread recognition as a framework to the understanding of the behaviour of soils. The same model is applicable to different materials such as sands and clays. A number of exercises, both solved and proposed, are presented, and a microcomputer program, "Cris", accompanies the text. It is used for training and simulation of the behaviour of soil samples subjected to triaxial tests through the critical state models. Undergraduate students of civil and mining engineering and engineering geology will find this text to be of interest.