In low- and middle-income countries, private sector providers often complement governments’ efforts to deliver and pay for vaccinations. This study used health facility data and client and provider interviews in Benin, Malawi and Georgia to estimate the percent of total immunizations performed—and the amount of funding contributed—by the private sector, and to assess the regulatory environment. The findings indicate the private sector’s role in immunization delivery is growing, and the authors suggest that countries enact policies and control measures to ensure high-quality and affordable service delivery.