A cohort analysis methodology is used in this article to study Chile's "new" middle classes. It describes the members of these cohorts and compares them with older cohorts that are still economically active. The relative size as of the 1990s and 2000s of these occupationally determined middle classes or strata are analysed, and a distinction is drawn between "new" and "old" cohorts. The question as to whether or not the emergence of new occupational cohorts correlates with differences in income is also explored. This analysis leads to the conclusion that a new middle class has taken shape that is composed of people who became full-fledged members of the labour force during the economic growth surge of the 1990s and 2000s. The upper stratum of these new middle classes occupies a preeminent position, and social class influences income levels.