This tutorial review illustrates how modelling can be used to understand the structure and properties of chiral surfaces formed by adsorption of molecular layers. The two major theoretical approaches for such modelling (Density Functional Theory and classical force-field methods) are briefly described and compared. A few examples of their use are given, focussing on: (i) the expression of chirality at the local and global scale in layers of chiral molecules, (ii) the appearance of chirality in layers of achiral molecules on achiral surfaces, and (iii) the molecular organisation in layers formed from racemic mixtures.