This seminar will address the various theoretical schools that have tried to explain ethnicity and ethnic conflict. The seminar takes a biocultural psychological approach. It will cover: 1) the psychological biases and intuitive assumptions that operate when people think about ethnicity, 2) the nature of ethnic categories as represented in the mind (and compared to other sorts of social categories), 3) The affective attachments that often characterize people's orientation towards their own ethnic category and neighboring 'others'. The seminar will delve widely into the psychological literature on groups, prejudice, stereotyping, and essentialism, and also into the anthropological, sociological, and political science literatures on ethnicity. The evolutionary origins of the ethnic form of social organization will also be explored, as will be the evolutionary origins of the psychological biases that are most important to ethnicity and ethnic conflict. It is open to graduate students and advanced undergraduates.