This book presents methods for analyzing trends in income inequality over time. The different innovative techniques which the authors have developed for the examination of changes in the size distribution of income, are for the first time described in a consistent and coherent fashion. The methods are based on the maximum entropy principle which is intuitively explained in the book. New ways to analyze Lorenz curves are introduced as well as new techniques for comparing income distributions (and the level of inequality inherent herein) both over time and across space. The book should be of interest to students, scholars and policy makers alike.