Soils exhibit macroscopic properties that are intimately related to their microscopic features. This intuitive statement has recently been more and more supported by the parallel development of high-quality experimental observations, at both micro and macro scales, and by the formulation of continuum-based constitutive models in which specific internal variables were introduced to account for the soil microstructure and its evolution. This contribution is aimed at illustrating some of the above experimental observations, the criteria adopted to properly select the related internal variables followed by their modelling within a thermodynamics-consistent framework, requiring the definition of an energy function and a rate of dissipation one. Reference will be made to possible forms of the above functions, discussing their efficacy in reproducing specific micro-driven aspects of the macro-behaviour of clays.