Stephen C. Carlson investigates the text of Paul’s Epistle to the Galatians and analyses how that text changed over the course of its transmission in manuscript copies over several centuries. For this study, he collated ninety-two textual witnesses of Galatians and arranged them into a genealogical family tree called a stemma codicum, with assistance from a computer-implemented method used in computational biology known as cladistics. Using this global stemma, he establishes a critical text for the epistle and assesses the nature of the textual variations that occurred throughout the text’s history of transmission in over 250 significant variant readings, paying particular attention to possible theological motivations. This is the first study to produce a global stemma of any kind for a New Testament book, an accomplishment that was previously thought to be unfeasible.