STORK’s main objectives are to identify existing eID infrastructures in Europe, specify and implement a common architecture which allows secure and easy to use eID solutions in Europe, and demonstrate the European interoperability. Pilot 1 “Cross-border Authentication for Electronic Services” focuses mainly on demonstrating that the existing online services in one Member State can interoperate with eID credentials issued in another Member State. The registration/authentication functions are central elements. The pilot demonstrates the cross-border usage with eServices like pre-filling of templates. The complexity of the pilot is technically based on the established interoperability of the two different architectures implemented in STORK. Support functions and common agreed release cycles are introduced as well as multi-lingual versions of the involved portals.