Catharine Brown (c. 1800-1823) was the first Cherokee convert with the American Board of Commissioners for Foreign Missions (ABCFM). After joining the “mission family” of the Brainerd Mission, Catharine gained fame through her letters, becoming the first Native American woman whose writings were extensively published during her lifetime. Her posthumous memoir, featuring heavily edited versions of her letters, saw widespread reprinting and acclaim. While scholars have begun to recognize her as a figure of Cherokee revitalization, they have yet to articulate her project and its significance. Analyzing Catharine’s letters and memoir, missionary records, newspapers, and correspondence from the Brown family, and drawing from fields such as anthropology, literary criticism, and religious studies, I argue that Catharine joined the mission family as a sister using a Cherokee idiom of kinship that converged with Anglo-American conceptions of kinship, and that she thus embodied a brief moment of possible cross-cultural kinship between Cherokees and white Americans. Catharine sought cultural revitalization and influence along Cherokee lines, at a time when missionaries, and the American public, sought to model proper familial relations to Native Americans. However, Catharine was partly an appealing figure because she was a celibate, mixed race “sister” who never married. Moreover, although Catharine successfully conformed to missionary expectations, she underwent considerable emotional strain in doing so. Her success in forging kinship ties with the missionaries ensured that her immediate family converted, and the ABCFM celebrated the Browns as being miraculously reformed. However, the window of opportunity that Catharine’s sisterhood opened for cross-cultural kinship abruptly shut with the debacle over Cherokee men marrying white women in Cornwall, Connecticut. The dissertation concludes in the late nineteenth and early twentieth centuries, when Catharine was memorialized in white and Cherokee circles in different ways. This dissertation explores the ethical issues of conversion and Catharine's posthumous memorialization, the promise of Christian siblinghood, and the limits and costs of belonging in the American national family in the early republic and beyond.