Can operations and implementation research guide today's unprecedented efforts to scale-up HIV/AIDS prevention, treatment, care, and support in resource-limited settings? Our study of patients with HIV/AIDS who were first seen at the Central Hospital (Yaoundé, Cameroon) to begin antiretroviral therapy demonstrates the value of using operations research to explore programs, policies, and guidelines used in health care. We studied one group of patients, those lost to follow-up. Our findings confirmed the value of early treatment, systems to follow individuals, free treatment, and resources that enable operations research. We encourage health-care workers and program managers to perform operational research in their own context, and we emphasize the importance of allocating adequate human, financial, and logistic resources for this activity. Finally, we stress that the health-care workers, program managers, and researchers must work together to better inform policy and guidelines.