This volume edited by María Encina Cortizo and Michela Niccolai (chercheuse au LaM-ULB) explores the different minor forms of musical theatre in the 18th and 19th century. It addresses the complex variety of stage works with sung and spoken sections, such as «vaudeville», «singspiel», «opéra-comique», «zarzuela» or «operetta» in different European countries from the eighteenth century to the beginning of the Twenties. Beyond a multifaceted perspective, twenty-one essays investigate the nature of these musical theatre forms, attending their origins, literary sources, relationships, vocality or cultural transfers, features that in some cases have made them become a mass phenomenon. The dissemination and adaptation of these genres through different national contexts, confirms the significance of the long-standing relationship between them and the contemporary dramatical and musical repertoire, revealing significant synergies, always conditioned by the market evolution.