This article throws new light on the troublesome question ‘what is popular music?’ by pursuing a genealogy of discourse in Britain during a crucial period from 1860 to 1920 in which modernity is increasingly characterised by an antagonistic relationship between intellectual elites and consumer entertainment. Focusing on London music halls, social reformism and ragtime, I argue that the term fell into two broad categories of use: first, to identify and/or denigrate mass culture; and second, to establish a pathway for edification and to champion ideals of respectability. Although implicated in the construction of binary oppositions and frequently associated with impropriety, the popular was not always associated with lowness. The idea, however, was shot through with contradictions deriving from a view of ‘the people’ as being simultaneously docile and seditious. Ultimately, I demonstrate that the popular is a floating signifier with the potential to reference mutually opposing ideas.