Beginning in the late 19th century an unexpected initiative by "Pariahs" in Madras Presidency to convert themselves to Christianity occasioned a series of fierce debates amongst missionaries that soon spread to the British administration and to the emerging native public sphere. The Pariah, long ignored, had suddenly become a "problem." By the early decades of the 20th century, the "Pariah Problem" and the governmental interventions targeting it, had completely transformed not only what it meant to be a missionary in South India, but also what it meant to govern. My research will examine the antecedents, forms and consequences of these debates and interventions. I will chart the ways in which settled assumptions -about such categories as religious and "civil" (as realms within a polity), spiritual and temporal (as distinct human motives), and the proper distribution of responsibilities across the social body- were thrown into crisis and renegotiated during this period. This research, while being historical in its focus, is of contemporary significance. For it was during that period that India's policy of caste-based "reservations" (affirmative action) was first implemented, the notion of caste as a "religious" phenomenon gained ascendancy, and the policy of governmental non-interference in religion took on a number of new and contradictory forms. The uneasy consensus forged at that time threatens to come apart today: "reservations" have become the site of a bitter struggle that has given rise to right-wing Hindu dominance in the political sphere; Dalits (today's Pariahs) increasingly protest caste discrimination by converting out of Hinduism en masse; and the government of Tamil Nadu (in erstwhile Madras Presidency) has arrogated the right to ban any religious conversion it deems to be "coerced." Yet current analyses of these events tend to reproduce the very categorical assumptions that my research will historicise.