How does the work of ethnographers contribute to policies they did not anticipate, policies they may even abhor? This article explores the ways 19th-century Europeans who would never have considered themselves as policymakers or even policy wonks – writers, artists, missionaries, and ethnographers – influenced colonial ‘native policy’. The article focuses on the case of precolonial European representations of Polynesia (Samoa in particular), tracing the effects of these discourses on the foundational process of colonial state formation in German Samoa after 1900. German colonialism in China and Southwest Africa is also discussed. Both the form and the content of ethnographic discourse influenced colonial interventions, even if these effects were dependent on a contingent array of other determinants. The conclusion discusses various ways in which ethnographers can try to see that their writings are not enrolled into political projects to which they might object.