Demographic aging causes substantial worker shortages. So far, policy debates neglect the aspect of age at labor market entry. We study the age at which young individuals first enter the labor market and how it has developed over the last four decades. Based on long-running administrative data, we describe birth cohorts from 1960 through 2000, and separately consider different types of employment entry. We investigate the entry age distribution and heterogeneities across demo-graphic groups. We find that conditional on employment, the median age of first holding a stable full-time employment increased by almost 4 years between the birth cohorts 1960 and 1995. Our decomposition analysis yields that more than one quarter of this increase is explained by higher educational attainment and the rising share of non-German workers, which appear to be the main mechanisms behind the delay in labor market entry. Additionally accounting for changed occupations, industry composition, and relative entry-level earnings explains about 40 percent of the ob-served delay in labor market entry. The role of different mechanisms varies across the types of employment entry.