This article discusses the development of social categories and ethnicity in the peninsula of Yucatán, Mexico, since the Conquest in the sixteenth century. Based on the Yucatec case, it demonstrates that ethnicity is not a ubiquitous form of social organisation, but rather a historical process related to specific techniques of social distinction. It argues that the starting point for the analysis of ethnicity should not be ethnic collectives, but instead the ways in which individuals use ethnic categories in social interaction.