A conceptual framework to analyze the importance of intervention design in expanding access to and utilization of health services in a systematic way in developing countries are discussed. Four dimensions of intervention designs required for the framework include characteristics of the basic intervention, characteristics of delivery, the requirements the intervention imposes on government capacity, and usage characteristics. the application of the proposed frame work to produce safe drinking water using solar disinfection is also presented. The proposed framework could also be used as a tool for health policy makers, planners, and program managers when considering the expansion of existing projects.