Critical state soil mechanics has provided an invaluable framework, essential for a proper understanding of the mechanics of many soils, both reconstituted and natural, at both small and larger strains. A limitation in its applicability results from robust forms of fabric in natural and reconstituted soils that mean that the critical states that can be defined in conventional tests do not correspond to a unique fabric. “Transitional” behaviour, in which the initial soil density plays a major role, seems also to result from robust fabrics. A number of examples of transitional behaviour are explored, emphasising that this type of behaviour does not threaten the applicability of critical state soil mechanics, but only the definition of intrinsic behaviour, such as we might require to examine the effects of structure. A range of behaviour appears from the examples, from very little convergence of specific volumes during compression or shear to a slow but gradual convergence. Even slow convergence, however, may still preclude the definition of normal compression and critical state lines that are independent of initial density within a useful stress range.