Since the early 1990s hundreds of thousands of Tamil villagers in southern India have participated in literacy lessons, science demonstrations, and other events designed to transform them into active citizens with access to state power. These efforts to spread enlightenment among the oppressed are part of a movement known as the Arivoli Iyakkam (the Enlightenment Movement), considered to be among the most successful mass literacy movements in recent history. In The Light of Knowledge, Francis Cody's ethnography of the Arivoli Iyakkam highlights the paradoxes inherent in such movements that seek to emancipate people through literacy when literacy is a power-laden social practice in its own right. The Light of Knowledge is set primarily in the rural district of Pudukkottai in Tamil Nadu, and it is about activism among laboring women from marginalized castes who have been particularly active as learners and volunteers in the movement. In their endeavors to remake the Tamil countryside through literacy activism, workers in the movement found that their own understanding of the politics of writing and Enlightenment was often transformed as they encountered vastly different notions of language and imaginations of social order. Indeed, while activists of the movement successfully mobilized large numbers of rural women, they did so through logics that often pushed against the very Enlightenment rationality they hoped to foster. Offering a rare behind-the-scenes look at an increasingly important area of social and political activism, The Light of Knowledge brings tools of linguistic anthropology to engage with critical social theories of the postcolonial state.