This dissertation explores the use of topics for dramatic purposes in Mozart's Così fan tutte. The five analytical chapters are organized around a central question: how do pastoral and fanfare topics shape the plot of Così fan tutte? Chapter 2 highlights the role topics and tropes play in emplacing and nuancing emergent meaning in the Così fan tutte motto. Chapter 3 examines transformative topical tropes in "Ah guarda, sorella." Chapter 4 shows how the horn fifths and fanfare topics in "Per pietà, ben mio" frame Fiordiligi's choice: the Albanian or Guglielmo. Chapter 5 illustrates the relationship between fanfare topics and galant recitative schemas to articulate formal boundaries between accompanied recitatives and arias. The expectations of closure emplaced by the examples from Così fan tutte nuance a reading of "Hai già vinta la causa!" from Le nozze di Figaro. Chapter 6 discusses the role of recitative intrusions and their articulation of the Count's unrest in "Vedrò mentre io sospiro." Detailed analyses and close readings of the topics and tropes in this dissertation drawn from throughout Così fan tutte showcase Mozart's rich deployment of topics in varied musical and dramatic roles.