The Independent Evaluation Group (IEG) has established three Strategic Engagement Areas (SEAs) around which it has organized its work program. One of those SEAs is Sustained Service Delivery for the Poor. This paper is one of two (the second one addresses behavior change) that will develop frameworks and tools to be employed to supplement IEG evaluations in urban transport, water and sanitation, and nutrition. This paper serves three purposes. First, it defines service delivery and its key concepts and features as well as provides examples of how the World Bank Group has supported service delivery. Second, the paper serves a practical purpose within IEG in developing a framework and analytical protocol to evaluate service delivery as part of three ongoing sector evaluations in urban transport, water and sanitation, and nutrition. Finally, the paper discusses how to integrate service delivery when designing and implementing other sector evaluations.