The impetus to write this book grew out of curiosity and frustration. For a research project in which I was involved, I wanted to select an appropriate index to measure inequality, so I searched for a book that comprehensively reviewed the available indexes, identified their operational similarities and differences, and clarified their theoretical undetpinnings. Discovering that no such book existed, I became increasingly frustrated and curious. It became evident that I would have to undertake my own systematic review of the literature, presumably in my own discipline, in order to identify the alternative measures and choose an appropriate one on the basis of proper theoretical and methodological criteria. This effort led to additional frustrating discoveries. First, I encountered a bewildering abundance of inequality indexeswell over ftfty distinguishable measures. Second, my review of the methodological literature on inequality measurement took me through the issues of literally scores of professional journals in five academic disciplines-economics, geography, political science, sociology, and statistics. Third, although I found some cross-disciplinary referencing of inequality measures, by and large each discipline's inequality measurement remained insulated from that of other disciplines.