Several early Christian texts describe Christians as a “new race” or “third race.” As N.T. Wright declares, this concept of a “third race” has been “both canvassed and attacked,” bringing notions of identity “into sharp focus.” According to Wright, the concept of being a “third race” marked off early Christians as both rooted and redefined, through both continuity and discontinuity. This paper will apply relevant “social identity” theory to the Martyrdom of Polycarp and the Epistle to Diognetus. Our comparison will further develop—yet essentially diverge from—Charles Hill’s investigation of similarities in vocabulary and ethos between the Martyrdom and Diognetus (including the role of imitation, the “sojourning” nature of Christians, and the exemplary endurance of the executioner’s fire). In Diognetus, Christians were to be shaped by their “new message,” forming a third race “distinguished from the rest of humanity” by distinctive communal-moral characteristics. The Martyrdom is saturated with first-person plural language, uses Polycarp as a community exemplar, and emphasizes the elect and righteous status of the Christian “race.” The commemoration of Polycarp’s martyrdom as imitatio Christi, patterned after the Gospel, was intended to motivate secondary imitation among the “whole race of the righteous.” This “God-fearing race of the Christians” was to exemplify the “great difference between the unbelievers and the elect.” In constructing this Christian identity, however, the Martyrdom unrealistically merges the Smyrnaean Jews and pagans into an amalgamated “other.” Nevertheless, focusing upon a communal-ethical rather than an individual-biographical purpose for the Martyrdom of Polycarp allows us to rise above continuing debates concerning the work’s authorship, dating, and integrity (cf. Holmes, Hartog, Kozlowski, and Moss), even while disagreeing with Hill’s assessment of the authorship of Diognetus. Both texts, although differing in literary genre and style, do aim at a similar purpose: the protreptic formation of communal character.