This paper reviews applications of cathodoluminescence scanning electron microscopy in the assessment of optical and electronic properties of semiconductors. The assessment includes, for example, information on band structure and impurity levels derived from spectroscopic cathodoluminescence, analysis of dopant concentrations at a level which is in some cases several orders of magnitude better than x‐ray microanalysis, and mapping of carrier lifetimes and defects. Recent advances in both the various cathodoluminescence techniques and the processes leading to electron‐beam‐induced luminescence in semiconductors are reviewed. Possible future trends are also discussed.