Early adulthood is often characterized by a phase of excess mortality. It is not dear whether this temporary increase in the risk of death occurs because of biological or contextual forces, nor whether this threat concerns all individuals of the same cohort. Age-specific mortality differentials from 10 to 34 years of age are calculated using a unique dataset that includes all individuals living in Switzerland born between 1975 and 1979. Certain risk factors act with variable intensity and follow patterns similar to the hump observed in the overall age-specific mortality risk. The results suggest that socioeconomic mortality differentials partly shape the hump. The division of the cohort into multiple subpopulations representing various leve...