The European Interoperability Framework underlying principles view models the motivation of the EIRA© in terms of goals to be achieved and the principles to be followed in order to achieve interoperability in public services. The interoperability principles are fundamental behavioural aspects to drive interoperable public services. They describe the context in which European public services are designed and implemented. The twelve underlying principles of the EIF are grouped into four categories: 1. Principle setting the context for EU actions on interoperability (Subsidiarity and proportionality); 2. Core interoperability principles (Openness, Transparency, Reusability, Technological neutrality and data portability); 3. Principles related to generic user needs and expectations (User-centricity, Inclusion and accessibility, Security and privacy, Multilingualism); 4. Foundation principles for cooperation among public administrations (Administrative simplification, Preservation of information, Assessment of Effectiveness and Efficiency).