We study how career incentives affect who selects into public health jobs and, through selection, their performance while in service. We collaborate with the Government of Zambia to experimentally vary the salience of career incentives in a newly created health worker position when recruiting agents nationally. We find that making career incentives salient at the recruitment stage attracts health workers who are more effective at delivering health services, conducting 29% more household visits and twice as many community mobilization meetings. Administrative and survey data show an improvement in institutional deliveries, child visits, breastfeeding, immunizations, deworming and a 25% reduction in the share of underweight children in the treatment areas. While career incentives attract agents who differ on observables—they have higher skills and career ambitions—91% of the performance gap is due to unobservables. The results show that incentive design at the recruitment stage can have dramatic impacts on the performance of organizations. (Coauthors: N. Ashraf, S.S. Lee.)