In the last few years, digitizations and reissues of historical recordings of Spanish zarzuela - from wax cylinders in the 1890s to long-play records in the 1950s - have revealed a range of contrasting vocal performance styles. By focusing on portamento, this Element sets the foundations for a contextually sensitive history of vocal performance practices in zarzuela. It takes stock of technological changes and shifts in commercial strategies and listening habits to reveal what the recorded evidence tells us about the historical development of portamento practices and considers how these findings can allow us to reconstruct the expressive code of zarzuela as it was performed in the late nineteenth century and how it transformed itself throughout the next half century. These transformations are contextualized alongside other changes, including the make-up of audiences, the discourses about the genre's connection to national identity and the influence of other musical-theatrical genres and languages.