The Swedish ethnologist Dag Trotzig (1914–44) spent almost two years of his short life in Latvia. On the recommendation of Sigurd Erixon, he arrived in Riga in 1938, soon after gaining his bachelor’s degree at Stockholm University, to take over the teaching of ethnography at the University of Latvia. This charismatic young researcher was able to do a good deal in this short period. His primary accomplishment was to significantly change the content and proportions of ethnology subjects taught at the university. He was also interested in the study of local culture and the popularisation of ethnology in Latvia, and he quickly became a familiar figure in the Latvian media. Finally, Trotzig was the main driver behind a Latvian cultural atlas project, which was begun in 1939. Through this young Swedish ethnologist, Latvia imported scholarly practices that had developed in another country. The present article discusses Trotzig’s achievements in Latvia: his popularisation of the concept of ethnology, his activities at the University of Latvia, and his role in the creation of the Latvian cultural atlas. It also tells the story of research developments in the interwar period: active international relations, transnational projects launched during this time, and the efforts of academics working in ethnology and folkloristics to define their fields of study.