The rapid expansion of HIV care and treatment in resource-limited settings will undoubtedly ameliorate conditions in communities ravaged by this epidemic around the world and enable persons living with HIV to live longer, more productive lives. Concerns have been raised, however, regarding the possible deleterious effects on other health services. This paper argues that efforts to scale up HIV care and treatment in resource-limited countries, if designed and implemented with the additional goal of achieving broad health benefits, may serve as a catalyst for the establishment of more effective and responsive health systems. In order to determine these broader effects, mechanisms need to be established that enable relevant research and evaluation questions to be answered.