This report shares lessons learned from The Merck Company Foundation's decade of experience building immunization capacity in Africa. The Merck Vaccine Network -- Africa, a philanthropic initiative to train immunization managers in Kenya, Mali, Uganda, and Zambia, suggests seven key lessons that can help other funders, governments, and NGOs designing or implementing similar vaccine delivery training programs improve the effectiveness and sustainability of their work. Merck's experience designing and supporting the initiative can offer valuable lessons for other actors in the immunization and broader global health fields who are engaged in or planning similar work. Specifically, we identify seven forward-looking lessons that can increase the effectiveness and sustainability of programs to build the capacity of the vaccine workforce in developing countries: