This thesis presents a new modelling method for information systems analysis and design, where the concept of service and the principles of service orientation are used for integrated modelling and reasoning about information systems architectures across organisational and technical systems boundaries. The concept of service enables cohesion of the intersubjective and objective modelling traditions by using a single type of diagram that facilitates detection of semantic inconsistency, incompleteness, ambiguity and discontinuity between the static and dynamic aspects of information systems specifications. The thesis is focused on three research topics, which are fundamental to the development of a new service-oriented modelling method. The first research topic concerns a pragmatic-driven specification of information systems. It clarifies answers to the research question: How can a conceptual modelling process be driven by pragmatic considerations? The second research topic provides a service-oriented modelling foundation for information systems analysis and design. It answers the research questions: How can the concept of service be used explicitly for the analysis and design of information systems and how can the static and dynamic aspects of information systems specifications be integrated at the conceptual level? The third research topic presents transition principles to implementation-specific design and answers the research question: How can service-oriented conceptual representations be aligned with implementation-specific design? The thesis contributes with a new knowledge to the area of conceptual modelling of information systems. The service-oriented modelling method consists of the modelling process, modelling language and techniques for the analysis and design of information systems on three levels of abstraction: pragmatic, semantic and syntactic. These three levels are necessary for a holistic understanding of enterprise architecture by stakeholders. The advantage of the service-oriented modelling method is that it can help to control traceability from information system design to original requirements. The method facilitates the semantic integration of the structural, behavioural and interactive aspects of information systems conceptual representations by using a single diagram type. The modelling language provides service-oriented constructs that are fundamental to building the major systems analysis patterns. The service-oriented modelling process contributes with seven steps of incremental design, which justifies various information systems components. The method provides the basis for a gradual and systematic way of modelling and an understanding of how pragmatic, semantic and logical information system requirements are linked together. The possibility to detect and eliminate undesirable characteristics of service-oriented diagrams can help to improve communication among stakeholders. Service-oriented specifications are computation-neutral and therefore they are more comprehensible for business analysis experts in comparison to implementation specific graphical representations of information systems. Finally, this thesis presents the challenges for future research, one of which is the development of the automated tools for the alignment of business models with implementation-specific information systems specifications.