In the Monobiblos, the characterizations of Cynthia and Propertius develop in traceable trajectories. The goal of this thesis is to provide a close analysis of specific poems in Propertius’ Elegies that contribute to and shape the development of characterization in the first book, as well as to show how Propertius’ and Cynthia’s characterizations interact with and build upon each another. In the first chapter I look at four poems that delineate the evolution of Propertius’ characterization from a victimized lover to a man who eventually accepts his situation and vows to love Cynthia for all time. In the second chapter I again examine four poems, this time with a view to Cynthia’s development. She begins as a master teacher and in the end becomes someone who has changed Propertius’ heart and tested him so that she is confident in his devotion to her.