Heavy‐metal oxide glasses might arbitrarily be defined as those containing over 50 cation percent of bismuth and lead which participate in the glass structure as network formers. Glass systems based on these heavy‐metal oxides in silicates, borates, phosphates, germanates, and ferrites are surveyed. Gallate systems are emphasized since they have a unique ability to form stable glasses while maintaining key properties, such as the best infrared transmission and the highest nonlinear optical susceptibilities and diamagnetic Verdet constants for oxide glas