AbstractMicrohardness indentation of thin PVD wear resistant films usually results in deformation of both the coating and the substrate and such tests lead to a‘composite’hardness number. Previous attempts at separating the contributions from coating and substrate to measured hardness will be reviewed and a new thin layer hardness model proposed. Examples of the use of this model for the determination of‘true’coating hardness will be given. These include an investigation of the effects of substrate bias on hardness of ion plated titanium nitride and the modelling of the hardness behaviour of soft nickel coatings and ion bombardment amorphized silicon.