Visualization of the spatial distribution of biomolecules with nanoscale precision is essential to understanding the molecular mechanisms of biological phenomena and diseases. Among several state-of-the-art visualization techniques, expansion microscopy (ExM) is an attractive tool, as it can achieve sub-20-nm resolution imaging of biological specimens, even with conventional diffraction-limited microscopy. This chapter first introduces the concept of ExM and its variants and then provides practical guidelines for implementing expansion microscopy and related techniques.