Present-day governments are experiencing a shift towards supplying demand-driven and personalized electronic services. This often requires that government organizations collaborate with each other and their services and processes need to be integrated to act in a coherent manner. In this paper, we take the diversity of government agencies as a starting point and focus on the development of a shared ontology to enable interoperability among heterogeneous business process and services of public agencies. This framework contributes to understanding the key concepts and relations that form the basis for coordinating the activities necessary for integrated public service delivery. The ontology is aimed at capturing the main elements to enable communication among and integration of the activities of decentralized and autonomous agencies. The ontology has been interactively developed by studying organizational processes, by conducting interviews and literature study. The proposed ontology can provide a foundation for an architecture blueprint that can enable demand-driven integrated service delivery in practice without having to pose detailed requirements on organizations. As autonomy is fostered, this research can potentially enable the integration of private organizations.