Millennials or Generation Y are people born between 1985 and 1994 (others say in the 1980s and 1990s). So yes, many of them are already well into their 30's. It is because they're still relatively young, or at least they used to be a decade ago, but time goes by so quickly. Now we have "Generation Z", which are those born between mid-1990's and 2010. Strictly speaking, the latter aren't Millennials, but people often misuse the term because Gen Z doesn't have a specific name.