Cathodoluminescence (CL) microscopy and spectroscopy are enabling techniques for the microcharacterisation of technologically important materials. Recent advances in SEM instrumentation have considerably expanded the microanalytical capabilities of the CL technique. In this paper, following a brief overview of the principles and practice of CL microscopy and spectroscopy, a number of examples are presented that demonstrate the utility of the technique for the microcharacterisation of advanced opto-electronic materials.