This thesis explores Karl Barth's use of John's Gospel in the Church Dogmatics. It seeks to read John with Barth, tracing the roles which the Fourth Gospel plays in his theology, while identifying gaps and distortions in Barth's use of John. Another interpreter of John, Rudolph Bultmann, is also significant: despite early parallels, much of Barth's theology is shaped by his deep disagreement with Bultmann. The first two chapters therefore discuss the beginnings of dialectical theology. Bultmann and Barth retreat from systems of thought which have overwhelmed theology and have changed its subject matter. They look to the scriptures in seeking to develop theology which is genuinely about God, but hold different assumptions about the place and form of revelation. Chapter 3 considers Bultmann's existentialist interpretation of John. Chapters 4 to 9 examine a series of different aspects of Barth's use of the story of Jesus in John's Gospel. Although Barth emphasises the picture of Jesus Christ shown through his actions, he is more of a strategist than a story-teller. He presents the Word made flesh in a way which allows him to restructure the whole of theology so that it looks towards Jesus Christ rather than fitting in with human systems of ideas. His emphasis on divine decision and his exploration of the content of theology contrast with Bultmann's focus on individual human decisions. The role of other characters is diminished, and the narrative sequence of the story is compressed and distorted by Barth's emphasis on the paramount significance of God's decision to be incarnate. The dualism of John's Gospel, which becomes a dualism of human decision in Bultmann's theology, becomes a dualism of knowledge and falsehood in the Church Dogmatics, in which the real drama of the story is not the interactions between the characters but the struggle to proclaim the truth. Chapter 10 contains some concluding reflections on the wider implications of John's Gospel, showing how Barth's retreat and restructuring could be followed by a process of reengagement with all areas of truth and experience.