My dissertation explores the history of German tropical medicine in European and African contexts, focusing on sleeping sickness research before WWI. The sleeping sickness epidemic, which began in 1898 and resulted in the deaths of at least 300,000 people in the Lake Victoria basin before the 1914, had a dramatic and irrevocable impact on both the lives of local Africans and the development of imperial public health agendas. I examine how research expeditions in East/Central Africa, jointly sponsored by tropical medicine institutions and European governments, were related according to changing scientific, cultural, and political circumstances. Specifically, I analyze the impact of microbiological laboratory and fieldwork practices, local European and African cultural contexts, and global social and political imperatives on the production of knowledge about sleeping sickness. The project demonstrates the importance of collegiality, collaboration, and rivalry in shaping research agendas, determining investigative practices, and building professional careers. Applying transnational and comparative methodologies to new sources, I examine together sleeping sickness research in Europe and Africa, building on historical analyses of imperial rivalry and cooperation as well as established histories and anthropologies of public health and the life sciences. This project therefore departs from previous historical scholarship that has focused largely on national styles of scientific research, impacts of imperial medicine, isolated scientific biographies, and histories of Africa focused on colonial boundaries to establish a transnational history of public health.