This dissertation consist of three chapters devoted to topics in Demography and Economic Inequality. The first chapter examines the impact of demographic change on household income inequality in the United States, both historically and prospectively. We emphasize the distinct roles of population aging and cohort replacement and develop a methodology to study their joint compositional effect on income inequality. In the process, we develop a novel methodology to aggregate subgroup Gini coefficients into a population-level Gini coefficient based on the principle of maximum entropy. We document that cohorts born later in the 20th century embody higher levels of income inequality compared to earlier-born cohorts, and we argue that much of the increase in inequality over the past two decades can be accounted for by demographic change. The second chapter studies inequality decomposition by population subgroups. We define properties of a satisfactory decomposition and ask what they imply for the decomposition of familiar inequality indices. We find that the Gini coefficient, the generalized entropy indices, and the Foster-Shneyerov indices all admit satisfactory decomposition formulas derived from a common set of axioms. While our axiomatic approach recovers the known decomposition formulas for the generalized entropy and the Foster-Shneyerov indices, it leads us to a novel decomposition formula for the Gini coefficient. The decomposition of the Gini coefficient is easy to compute, and it has both a geometric and an arithmetic intuition. The third chapter analyzes historical census data and documents that the fertility decisions of Armenian, Georgian, and Azeri parents living in Soviet-era Russia in the late 1970s and the 1980s were significantly more son-biased than the fertility decisions of Russians, Eastern Europeans, and Central Asians. We interpret this finding as evidence that the recent increase in the sex ratio at birth in the Caucasus is at least partially reflecting deep-rooted cultural preferences for sons.
