The overall objective is to ensure an efficient and sufficient level of system services are provided to facilitate meeting world leading levels of RES-E while maintaining the level of resilience that consumers and society have come to expect from the European electricity system. This requires defining the right amount of flexibility and system services to support transmission system operators using a threefold approach. Firstly, the technical needs of the pan-European system will be defined for scenarios with more than 50% RES-E in will be identified and translated to services and products to be delivered in an enhanced market design. Secondly, the electricity market design and regulation needs to be augmented to efficiently and effectively procure the appropriate combination of these system services. Thirdly, implicit and explicit barriers to competitive forces being applied need to be removed. This requires an in-depth understanding of all stakeholders’ roles (Generation and flexibility providers, Transmission system operators (TSO) and Distribution System Operators (DSO) and regulators) at all system levels (interconnected system, national transmission and distribution sub-systems and consumers). For doing so, EU-SysFlex joins a multidisciplinary team of 34 partners from 14 European countries, led by the (Transmission System Operators) TSOs representing four different synchronous systems that integrate the pan-European interconnected electricity system: EirGrid & SONI (Ireland), PSE (Poland), AST (Latvia), Elering (Estonia), supported by the necessary (Distribution System Operators) DSOs, technology providers, and research & experienced entities. In addition, a group of three other European TSOs: Fingrid (Finland), LitGrid (Lithuania) and Ceps (Czech Republic), will join the advisory board of the project, in addition to EDSO for Smart Grids and USEF, in order to help the project maximising its impact.