Polymer nanocomposites are attracting increasing attention due to their potential benefits in improved performance, for example in enhanced barrier properties for packaging applications and better conductivity for EMF shielding applications. However, without proper dispersion of the nanoparticles within the polymer matrix the potential property enhancements of the nanocomposites will not be fully realised. Currently, methods for assessing the dispersion of particles in the polymer are not suited for quality control. This review assesses the potential of rheological and thermal methods for characterising the extent of dispersion of nanoparticles in polymer nanocomposites. Furthermore, it discusses some of the issues that affect the reliability of data obtained using "imaging" techniques, principally TEM and XRD, for assessing nanocomposites dispersion.