Abstract
Dramatic changes in the ethnic composition of countries in the last decades have sparked new interest among social scientists in studying and uncovering the role of ethnic diversity on social, political and economic outcomes. Yet, most ethnic fractionalization indices used by scholars to study these effects treat ethnic heterogeneity as time-invariant, thus concealing its long-term effects. However, failing to take into account historical developments in ethnic composition might seriously hinder our understanding of their effects on social, economic, and political outcomes. This paper introduces a new dataset containing an annual ethnic fractionalization index for 162 countries across all continents in the period of 1945–2013. The Historical Index of Ethnic Fractionalization (HIEF) dataset is a natural extension of previous ethnic fractionalization indices. It offers the opportunity to study the effects of ethnic fractionalization across countries and over time. The article concludes by offering some preliminary descriptive analysis of patterns of change in ethnic fractionalization over time.