Today, e-Government is an emergent multidisciplinary research ï¬eld that has the aim to support the delivery of electronic information and services to citizens, businesses, and other stakeholders. This vision should be based on an effective cooperation between Public Administrations (PAs) that need to be more and more organized to delivery value-added e-Government services. Such cooperative environments should interconnect several PAs using interoperability architectures exploiting the service-oriented paradigm. Service-orientation provides a general framework to enable interoperability allowing different systems to exchange data, participate in business processes, and cooperate to reach a common goal. Furthermore, a strong relationship between the e-Government high-level service concept and the more technological service concept used in Service Oriented Architectures has been found analysing current research. In this thesis I propose some design guidelines for the engineering of service- oriented systems for the delivery of e-Government services. The role of metadata is discussed as a fundamental for the development of interoperability architectures inside the domain and a central role has given on documents production and description. Moreover, some approaches to testing and veriï¬cation are showed to improve the development of the service-oriented backend of Public Administrations. Although these approaches has been studied and developed in e-Government domain, some of them can be applied in generic service-oriented systems.