Social inequality has grown dramatically in many societies over the last several decades, compelling attention to its causes and consequences. This chapter reviews the issue of life course inequality from a cohort-based perspective. Much work using this approach has focused on economic inequality, often emphasizing its links to health and other consequential domains. The tendency for economic inequality to increase over the life course has been observed in numerous advanced industrial societies. Both sociological and psychological accounts have been offered to account for this phenomenon. In sociology, the cumulative dis/advantage (CDA) approach has identified social processes operating at macro-, meso- and micro-levels that serve to generate and sustain increases in inequality over the life course, By contrast, the notion of psychosocial accentuation is sometimes advanced by psychologists to suggest that increasing inequality results from individual-level differences in talent and effort. One way to ‘test’ these two competing hypotheses – both purporting to account for intra-cohort increases in inequality – is, ironically, to examine within-cohort patterns comparatively between cohorts, or across societal settings. That is because if trajectories of inequality are influenced by social processes, they could be expected to vary between cohorts (or societies) that encounter different social policies and/or historical events. However, if increasing inequality occurs as a simple consequence of the distribution of individual talents, such trajectories should be little disturbed by historical events, policy innovations or other forms of social change. Available evidence suggests that, at least for the measure of income, changes in economic conditions, social policy and other relevant characteristics have been associated with alterations in the patterning of life course inequality.