This article examines the way Paul seeks to justify his claim in Gal 4:24 that the story of Hagar, Sarah, and the two sons whom they bore to Abraham is to be understood as an allegory of two covenants bearing children (respectively) for slavery and freedom, and explores the implications for Christian theological interpretation of Scripture. Recent interpretations of the passage range from those that represent Paul as bringing to the text of Scripture the interpretive warrants for his appropriation of the text to those that represent Paul as deriving his interpretive warrants from within Scripture itself. I propose a reading that resists polarization between these two alternatives, tracing the various interwoven threads of inner-biblical intertextuality, salvation-historical narrative, apocalyptic revelation, apostolic ethos, and Galatian experience within the argument that supports Paul's allegorical appropriation of the Genesis story, and highlighting the fusion of dramatic and persuasive functions that the allegory serves within Paul's deliberative rhetoric. Understood in this manner, Paul's interpretive practice in Gal 4:21–5:1 does not provide a global warrant for speculative allegorization. It does, however, provide an apostolic precedent for figural readings that cohere with the narrative logic of salvation history and contribute to the formative and directive functions of Christian doctrine within the life of the church.