The concept of the 'mainstream‘ is a contested one in popular music studies. In some cases, the term is used to signify an Other of the alternative and the subcultural; in others, the term is used more positively to represent sets of cultural, economic and institutional practices that contribute to the popularity of certain forms of musical production and consumption. The papers presented at the conference Stuck in the Middle: The Mainstream and its Discontents, and the selection of those published in this volume, reflect the diverse and disputed nature of the concept of the 'mainstream'. They consider not just a single mainstream but a range of possible mainstreams, and open up some productive avenues for exploring this contested terrain.