Health sector decentralization has created an urgent need to strengthen public health management capacity in many countries throughout the developing world. This article describes the establishment of a national management training network in Vietnam that used Project-Based Learning to strengthen management competencies of HIV program workers and linked training to measurable improvement in HIV/AIDS public health program outcomes. Skills were taught using a combination of classroom learning and mentored fieldwork. From 2005 to 2015, 827 HIV/AIDS program managers were trained with this method throughout Vietnam by trainers in 3 regional training centers. A total of 218 applied learning projects were carried out by trainees during this period; 132 resulted in measurable improvements in HIV/AIDS program outputs, and 86 produced well-organized plans for implementing, monitoring, and evaluating HIV/AIDS intervention strategies. Vietnam's management training network represents an important advancement in public health workforce development that helps prepare workers for new roles and responsibilities in a decentralized health system.