This paper studies the ideology of government officials and coercive policymaking by studying the Indian Affairs office and the detailed reports of its bureaucrats who held authority over the land, education, and legal governance of Indigenous populations in the United States. We digitize the agency's archival records and use computational tools to conduct large-scale analysis on the strength of support for the organization's assimilationist policies and goals among members of its workforce during the 19th and early 20th centuries. We document major shifts in ideological commitments that coincide with the entry---and eventual exit---of social reformers nominated for high-level agency positions by religious organizations. We find that ideology within the bureaucracy appears to moderate around the turn of the century despite the organization's overall continued pursuit of major assimilation policies, such as the promotion of farming and enrollment in off-reservation Indian boarding schools. To examine performance implications of ideology within the bureaucracy, we conclude with an analysis of policy implementation after the passage of the Dawes Act, a landmark law that aimed to dismantle collective land holdings. We provide evidence showing that the agencies with local staff who express greater past commitment to assimilationist goals carried out more land redistribution immediately after Dawes became law.