Using data covering over 100 birth-cohorts in 32 countries, we examine the short- and long-term effects of economic conditions on mortality. We find that small, but not large, economic booms increase contemporary mortality. Yet booms from birth to age 25, particularly those during adolescence, lower adult mortality. A simple model can rationalize these findings if economic conditions differentially affect the level and trajectory of both good and bad inputs into health. Indeed, air pollution and alcohol consumption increase in booms. In contrast, booms in adolescence raise adult incomes and improve social relations and mental health, suggesting these mechanisms dominate in the long run.  (JEL Codes: H51, I10, I38, N10).