Margherita Costa (c. 1600–after 1657) was one of the most prolific female authors of seventeenth-century Europe. As a singer and rumoured courtesan, she made her way in the courts and theatres of Rome, Florence, Turin, Paris, Venice, and perhaps even Germany. Costa was a virtuosa performer on both stage and page: between 1630 and 1654, a period marked by a decline in secular women’s writing in Italy, she produced fourteen full-length printed works across a remarkable range of genres, topics, and registers. Her unique position on the margins of courtly society allowed Costa to move more freely across the literary stage than any other female writer of her generation, switching easily between high and low style, decorous elegance and erotic allusions, encomiastic speeches and satirical parody. This literary versatility, combined with her talent as a performer, earned her the support of an enviable collection of elite patrons, including the Medici, the Barberini, the French royal house, and the Dukes of Braunschweig-Lüneburg. Though this charismatic virtuosa inspired admiration in her contemporaries and left behind an astounding literary legacy, her oeuvre remains understudied. This dissertation is the first study to take a more comprehensive approach to Costa’s trajectory as a virtuosa on the literary stage of the Seicento, from her early works in Florence in the 1630s to her last full-length publication in Venice and final printed poems in the 1650s. Rather than only focussing on one period of her literary career, the central aim is to give readers an understanding of her extraordinary adaptability in different cultural and patronage contexts. Costa’s journey opens a window onto the society and culture of a travelling musician and woman writer with a striking ability to succeed in an environment increasingly hostile to female public engagement.