EOSC-Pillar contributes to the implementation of the European Open Science Cloud, leveraging national initiatives of the EU Member States and thematic initiatives developed by research communities to build a future based on Open Science and FAIR data practices. EOSC-Pillar gathers representatives of the fast-growing national initiatives for coordinating data infrastructures and services in Italy, France, Germany, Austria and Belgium. The project aims to propose initiatives for the national coordination of data infrastructures and service recently started in many Member States as one of the founding pillars for the development and long-term sustainability of the EOSC. EOSC-Pillar starts with an initial group of neighbouring countries who are active in open science, to define and set a model to harmonise and interfederate the initiatives. The real challenge here is that, despite having very similar objectives and visions, and similar compositions, the initiatives adopt different approaches, need to abide by different national laws and regulations, and have very different funding models and relations with the decision makers. For this reason, the task of harmonising the different national experiences is not trivial; to succeed means to bring in the picture all the advantages resulting from the adaptation to national peculiarities. EOSC-Pillar takes the challenge to build on such specificities and heterogeneity to enhance the level of collaboration among all the countries bringing a rich and well organised contribution to EOSC. In a motto, “pursuing unity in diversity”.