The process of nanoindentation causes physical phenomena not only at the nano-scale, but at multiple length scales up to the macroscopic. This thesis investigates multiscale modelling of nanoindentation that links atomistic scale molecular dynamics (MD) to a finite element (FE) model in order to extend the length scales that can be modelled. Existing multiscale models are investigated and the relevant advantages and disadvantages of each are discussed. New coupling techniques are developed in both 2D and 3D, which are applied to nanoindentation test simulations to verify the models. A new force attribution 3D multiscale model is applied to some studies of nanoindentation of Au and Fe. The results are compared to those obtained through experiment and to atomistic only models to investigate the effect of the embedding continuum region. These studies show that by extending the length scales, long range effects of nanoindentation can be modelled in the far field by continuum mechanics giving results that are in closer agreement with the experiment. The new coupling method has wide application and a study of laser ablation of Au has been carried out to show that the multiscale modelling technique can be used to improve the description of this phenomenon also.