Health systems can primarily improve the health of individuals and populations by delivering high-quality interventions to those who may benefit from them. We propose a concept of effective coverage as the probability that individuals will receive health gain from an intervention if they need it. Understanding the extent to which health systems are delivering key interventions to those who will benefit from them and the factors that explain gaps in delivery are a critical input to decision-making at the local, national and global levels. We develop an integrated conceptual framework for monitoring and analyzing the delivery of high-quality interventions to those who need them. This framework can help clarify the inter-relationships between notions of access, demand for care, utilization, and coverage on the one hand and highlight the requirements for health information systems that can sustain this type of analysis. We discuss measurement strategies and demonstrate the concept by means of a simple simulation model.