Thesis advisor: Boyd Taylor Coolman / This dissertation investigates Thomas Aquinas’s understanding of the charisms (gratiae gratis datae) as distinctly social or ecclesial graces in light of his critical engagement with the Franciscan Summa Halensis. It first looks at the Summa Halensis’s christology and theology of the charisms to show the theological inseparability of charismatic grace from the threefold grace of Christ (the grace of union, capital grace, and the grace of the singular man). I then trace the development of Aquinas’s understanding of Christ’s humanity (in terms of the grace of Christ’s humanity) as a conjoined instrument of the Word and show how at every step Aquinas critically engaged the christology of the Summa Halensis. I bring that historical development in christology and its application to the sacraments to bear on Aquinas’s understanding of the charisms as social or ecclesial graces, graces given to one person for the sake of another’s salvation. Instrumental causality provided Aquinas a new conceptual framework with which to understand what it might mean for the charisms to be social graces, placing the charisms within a wider array of created causal agents in the economy of grace. I place this development within the context of the rise of Joachite prophecy as well as the secular/mendicant conflict at Paris, factors that motivated Aquinas to conceive these graces as distinctly mendicant charisms. Just as the development of instrumental causality in Christology propelled Aquinas’s understanding of charisms as social graces, so this application of instrumental causality reciprocally informed Aquinas’s account of the charismatic Christ in the Tertia Pars of the Summa Theologiae. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Theology.