During the establishment of modern society, luxury consumption played an important role as a symbolic reference for status comparison across class boundaries. But luxury has lost in contemporary sociology the theoretical importance it had in classical sociology. This article develops a historico-sociological explanation for this situation. In a first section, it debates on luxury in the 18th century, in which changing evaluations are interpreted in the context of broader semantic changes reflecting the ‘de-traditionalisation’ of social structure. Then selected conceptualisations of luxury in classical sociological approaches, including that of Sombart, Simmel, and Veblen are discussed. These classical accounts are the main reference for common sociological concepts of luxury. They also provide a context for understanding the differences between European and US American social structure and semantics. In the last two sections, the argument is that the consumer behaviour of elite members lost the key social function it had in 18th and 19th centuries because of the advent of mass consumption, mass media, and the cultural dominance of middle class consumer habits which were observed first in the US. As a result, then, the attention of sociological research now lies on the more subtle distinctions within the highly differentiated stratum of the middle class. At the same time, material and behavioural patterns of luxury are displayed not by concrete members of a group of the super-rich, but virtually in a mass media based celebrity system, leaving the rich more and more out of the sight of sociological observation.