This dissertation explores the distinctive intellectual history of South Asian multilingualism. Specifically, it focuses on the South India based Śrīvaiṣṇava religious community (c. tenth century CE onward) as a paradigmatic case. It analyzes the Sanskrit and Manipravalam, a mixture of Tamil and Sanskrit, production of theological treatises on the doctrine of self-surrender—a defining feature of the Śrīvaiṣṇavas—to reveal the dynamic interplay between the development of self-surrender and linguistic changes. Expanding on existing studies of Śrīvaiṣṇavas and self-surrender, this work demonstrates that different languages need to be considered in understanding the medieval Śrīvaiṣṇavas’ doctrine of self-surrender. I argue that the Śrīvaiṣṇavas’ linguistic multiplicity provides not only conditioning factors for the doctrinal development but also the possibility to harmonize any theological tensions. The chapters in this dissertation collectively offer insights into how precisely religious authors from the twelfth to the fourteenth century theorized self-surrender in Sanskrit and Manipravalam through specific historical conjunctures between this doctrinal development and linguistic movements: formation, systematization, heterogeneity, distillation, and harmonization. Based on the case study, this dissertation also challenges Pollock’s (2006) binary paradigm between Sanskrit and the vernaculars, showing that it cannot do justice to the highly diverse and fluid multilingual domain of premodern India. To better capture the complexity of South Asian multilingualism, it offers a new framework for understanding language as not only a linguistic medium but the sphere of related representations—of norms and modes of expression that are constantly negotiated and expanded by the agent—specific to social and intellectual circumstances.