Rowe's (1962) stress-dilatancy relationship for sand, and Schofield and Wroth (1968) (Roscoe et al., 1963), and Roscoe and Burland (1968) energy equations for soft clays are classical work in describing the stressdilatancy behaviour of sand and clay. However, the stress-dilatancy behaviour of soils is affected by the stress and strain paths followed by the soil and it is difficult to use a single equation to model the stress-dilatancy behaviour of all soils. In this paper, the historical development of the stress-dilatancy theories is briefly reviewed. The generalised stress-dilatancy behaviour of clay and sand is presented. Comparisons between the experimental observations and the theoretical predictions are made. The suitability of different stress-dilatancy theories to different soils under different testing conditions is examined. The data presented can also be used to examine other stress-dilatancy theories proposed by other researchers.