This book considers the relationship between commedia dell’arte and early operatic forms, from the court operas of the first years of the seventeenth century, through semi-private productions in Rome, to the public stages of Venice over fifty years later. While musicology has largely ignored the commedia dell’arte, except in cases of specifically comic opera characters, this book offers a corrective. A substantial re-contextualisation of the term “commedia dell’arte,” in line with recent scholarly developments in Italian-language theatre studies, emphasizes the partial nature of standard musicological treatments of the genre. The importance of serious commedia dell’arte characters is articulated, with particular attention given to the prime donne innamorate and the use of lament. Through a series of case studies based on commedia dell’arte plays, musical performances, pedagogical texts on acting, and several of the century’s best-known operatic works, the book argues that sound itself functioned as a crucial and influential component of commedia dell’arte dramaturgy. Furthermore, the author argues that the aural epistemology of the commedia dell’arte theatre—in which the gender, class, geographic origins, motivations and predilections of each character were audible in their voice—trained Italian audiences in habits of listening that rendered the musical drama of opera verisimilar according to existing dramatic norms, thus underwriting the success of the genre.