This paper provides the first experimental evidence on the long-term effects of work-study programs, leveraging a randomized lottery design from a national program in Uruguay. Participation leads to a persistent 11 percent increase in formal labor earnings, observable seven years after the program. Effects are stronger for youth who participate during pivotal educational transitions and are larger for vulnerable youth and men, while remaining positive for women and non-vulnerable youth. The program is highly cost-effective, with average impacts exceeding those of job training programs and comparable to early childhood investments.