This article reviews the range of emulsions, photochemistry, and processing techniques that have been proposed and put into practice for the successful mak- ing of display holograms. It covers various types of media including gelatin-based emulsions and photopolymers (it focuses on the former) and considers external factors that affect the final results. This is a compact review of the history of the field but focuses on the range of easily available commercial emulsions, as well as certain accounts of how to make holographic emulsions from scratch. It considers various combinations of developer, bleach, and redeveloper, which have been used to achieve the best of various trade-offs for such factors as resolution, contrast, dif- fraction efficiency, clarity, color quality, blackest blacks, and resistance to printout. It describes a recent advance in hypersensitizing holographic emulsions.