This introductory chapter sets out frameworks for understanding the relationship between music and emotion on the Caroline stage. The chapter begins by bringing major recent scholarship on emotions together with scholarship on music, before exploring some of the theories and beliefs about how emotions were understood, experienced, and expressed in the early modern period. It turns to the work of Robert Burton, Phillip Stubbs, and William Prynne who all discuss the theory that music could influence its listener’s emotions and behaviours. The chapter discusses some of the musical forms and instruments that were regularly heard in the Caroline theatre and concludes by setting out the primary sources that are examined in this book as case studies to demonstrate how music and emotions were intimately linked on the Caroline stage.