This thesis contributes to two fields of macroeconomics. The first two chapters contribute to the literature that investigates the role of household heterogeneity, in terms of marginal propensity to consume and labor income, for the 'optimal' design of fiscal policies. The first chapter explores how the introduction of household heterogeneity alters the prescriptions derived from the standard optimal fiscal policy framework that only accounts for a representative agent. When heterogeneity is accounted for the government uses taxation and transfers as a redistributing device that only partially corrects for fluctuations in income inequality. The second chapter builds on the results of the first. It develops a quantitative model that is estimated with US data on income and consumption dispersion among households. The model is then used to assess the relevance of the actual US fiscal policy. Unexpectedly, it concludes that the US fiscal policy is close to optimal. The third chapter contributes to the literature that is at the crossroad of the fields of history of macroeconomics and of macroeconomic pedagogy. It aims at reflecting on the theory used in the first two chapters of the thesis and in the teaching of macroeconomics. It identifies and discuss the deep methodological discrepancy between the theory used in research and graduate macroeconomics courses, on the one hand, and in undergraduate macroeconomic courses, in the other hand.