This chapter elaborates upon the notion of music worlds through a discussion of the work of Howard Becker and other relevant writers. It addresses how these worlds come about and how, in particular, punk and post-punk came about. Both 'subculture' and 'world' were formulated in the work of the Chicago School sociologists. In British sociology, the concept of subculture acquired a more specific meaning, following its appropriation in the work of Birmingham's Centre for Contemporary Culture Studies (CCCS). Subcultures, as the CCCS define them, are networks of working-class youths characterised by: the music they listen to; styles of dress, argot and ritual; distinctive activities; territories which they claim as their own. The CCCS's chief concern is working-class youths' resistance to domination. Music is important to this when and to the extent that subcultures identify with specific musical genres.