Inequality and mobility are two aspects of the longitudinal distribution of income. Mobility is socially valuable when it acts as an income equalizer across time. However, longitudinal income mobility analysis masks some features of the distribution of income along the life-cycle of the individuals, implying that panel income might not be representative of the long-term position of the individual in the distribution. Despite increasing empirical contributions brought on this domain, still little is known about the normative implication underlying the assessment of the heterogeneity in income-age trajectories of individuals belonging to the same cohort, and their connections with panel mobility. The objective of this project is to provide the normative foundations for the analysis of the heterogeneity in income-age trajectories (IAT). For this purpose, IAT is considered as a multidimensional distribution of income across individuals, where the dimensions are represented by the years in the life-cycle where income is measured. We will derive partial and complete orders of IATs heterogeneities, and study their characterization in terms of welfare orderings and statistical concepts, and define empirical tests for these orders. We will also consider the role of the family in shaping intertemporal inequality and lifetime disposable income inequality by investigating the relations between the heterogeneity in the family income trajectory across time and the spouse individual disposable IAT. We plan to use survey and administrative HHB historical data for Italy (1861-1961) for the empirical implementation of our methods, to construct statistical models of IAT and to study how different features of the IAT predicted from these models better explain lifetime income inequality and annual mobility.