During the Golden Age of children’s literature (1865-1914), authors both clung to the Romantic ideal of the innocent child and desired to acknowledge the child’s capacity for agency. This Romantic ideal of innocence was necessarily threatened by the child’s potential for agency—the more power the child wielded, the more likely she was to have her innocence tainted by experience and knowledge. This dissertation contends that the tension between the ideas of the child as innocent and the child as powerful led to the invention of a trope that I have named the “fantastic journey.” The fantastic journey occurs when a child character travels to a marvelous space (such as fairyland), has an adventure there, and returns to her ordinary world without her adult guardians ever discovering that she has been away because the journey has been either an out-of-body or an out-of-time experience. The journey may be explained as a dream or vision, or as an instance of time travel where the child returns to the same moment that she left in her ordinary world. The purpose of the fantastic journey is to allow a child to wield agency without any damage to her essential child identity. Each journey does this in different ways, but all allow child characters to gain knowledge and experience or to perform actions that would normally cause them to move closer to adulthood without losing any part of their child identity. Additionally, the journey also results in metamorphosis—abrupt change that is not the result of progress or process—for the child. This change always either enhances or protects the protagonist’s essential child identity. It is not change toward adult maturity. This dissertation traces the development of the fantastic journey through five texts, beginning with its initial formation in The Water-Babies; continuing through its various forms in Alice’s Adventures in Wonderland, At the Back of the North Wind, and The Story of the Amulet; and concluding with its deconstruction in Peter Pan.