Ethnicity has become prominent in popular and scholarly thinking over the last 50 years. In the late 1960s a few key works stimulated the growth of a complex body of literature, now defined by four main theoretical approaches. New insights are also emerging. Chief among these is the importance of integrating intersectionality into ethnicity theory. The Institute of Development Studies (IDS) has also made important contributions to this literature and its application to development studies. This article identifies three new frontiers in the study of ethnicity. First, theoretical effort is required to unpack how ethnicity intersects with other forms of identity. Second, as demonstrated by IDS’ contributions, further research is required on the impacts of ethnicity upon development and vice versa. And, finally, the geopolitical landscape emerging since 9/11 has stimulated major shifts in conceptions of ethnicity. These shifts and the resulting new framings of identity (ethnic and otherwise) beg investigation.