This Good Practice Guide describes a range of materials models that are suitable for use with rigid (glassy) adhesives and adherends. Reference is made to models for linear elastic and viscoelastic behaviour, but emphasis is given to elastic-plastic models that are needed to describe the non-linear behaviour of tough adhesives. Some of the limitations in the use of these models with rubber-toughened adhesives are explained and illustrated with extensive data on a toughened epoxy. A new model that is still under development is introduced that includes the contribution to plastic deformation from cavitation of the rubber particles under certain stress states. Selected test methods for bulk and joint specimens are described that can be used to determine the property data and parameters required by these models.