The study of human diversity in the first half of the 19th century has traditionally been categorized as a type of armchair-based natural history. If we are to take seriously this characterization of the discipline it requires further unpacking. Armchair anthropology was not a passive pursuit, with minimal analytical reflection that simply synthesized the materials of other writers. Nor was it detached from the activities of informants who were collecting and recording data in the field. Practitioners in the 19th century (...) were highly attuned to the problems associated with their research techniques and continually sought to transform their methodologies. The history of British anthropological research is one of gradual change and the adoption of new observational techniques into its methodologies. This article looks at the history of 19th-century British anthropology and examines in detail the observational practices of its researchers. In doing so it aims to answer the question: What is armchair anthropology? (shrink)