This thesis explores the interconnected processes of disguise and forgetting in two Middle English romances, Havelok the Dane and Sir Isumbras. The disguises in these two texts have a transformative function because the protagonists, while disguised, forget their identities. Because of this, these transformative disguises are immersed in the genre's well-established narrative of identity construction. The disguise motif, though common in romance, is rarely studied as a driving force in identity transformation because it more often functions as a performative plot point. Using medieval theories of memory, forgetting, and recollection to assess how the processes of disguise and forgetting occur in the texts, my research has determined that forgetting makes the transformations into disguise more complete and that recollecting what is important for both the true and disguised identities creates an improved and changed final identity. Overall, these romances' use of disguise, forgetting, and transformation presents forgetting as both a problem and a necessity for effecting change.