Although many Barth scholars have begun to argue for the necessity of evaluating Barth's theology as an interpretation of scripture, so far these efforts have focused more on hermeneutical questions and less on the specifics of Barth's exegesis, the specific ways his conclusions derive from that exegesis, and the interplay between his exegetical work and his theology. Accordingly, this article seeks to contribute to Barth studies by tracing the development of Barth's christology through his exegesis of Romans 5:12–21 in the first edition of the Romans commentary and Barth's later essay Christ and Adam – specifically how he understands the function of Christ's particularity in relation to his universal soteriological significance. These works have been selected not only because they give extended treatments of the text but also because there is a wide timespan between them. Furthermore, in contrast to the second edition of Romans and the Church Dogmatics, these texts remain relatively untapped, and will consequently provide a unique entry-point into Barth's exegetical work. By looking at Barth's theological development through his exegesis of Paul's text, we have a benchmark by which both to trace Barth's development and to critique it: does Barth do justice to both the particular and universal aspects of the christology of Romans 5:12–21? In this way, I intend to take seriously Barth's recurring assertion that his project succeeded or failed by how well it functioned as biblical interpretation. It will be demonstrated that the early Barth was unable to allow Christ's particularity to have much of a soteriological function in his interpretation of Romans 5:12–21, and was thus compelled to downplay the particularity of Christ which is emphasised in the text and instead emphasise his universality as the only aspect of soteriological value. By contrast, the later Barth grounded Christ's universality precisely in his particularity; that is, the Christ-event only had universal soteriological consequence because it was the action of a particular, historical Jesus. Yet, despite any problems we might find with Barth's interpretations, both works display Barth as an interpreter seeking to grapple with the nuances of scripture and with one of the central issues of the biblical text, and of soteriology in general: the relation of the one to the many.