This article focuses on archival collections relating to so-called “tattare” and “zigenare” (approximately meaning “tinkers” and “gypsies”) created by Swedish folklore scholars during the twentieth century, and how these scholars influenced politics and interventions regarding these categories. It addresses questions regarding the production of knowledge about these categories and the contexts, structures and actors that have created the basis for these kinds of collections. Special focus is on works by the folklore scholars Carl-Martin Bergstrand and Carl-Herman Tillhagen, and collections at the Institute for Language and Folklore, Department of Dialectology, Onomastics and Folklore Research and the Nordic Museum Archive. By unfolding the networks of Bergstrand and Tillhagen and following the traces of their work to other archives, the article highlights some of the political and monitoring dimensions in archival practices in relation to minority groups in Sweden.