This article analyses changes in the instability of labour incomes in Greater Buenos Aires between the late 1980s and early 2000s. It aims to study the impact of those changes on different individual and household groups, and then to evaluate the influence of current-income variability on income concentration. For the latter, the average inequality of current incomes is compared with the inequality of average (i.e. more permanent); incomes. The results obtained strengthen the argument for combining cross-section with other data that track the income paths of individuals through time.