Over the past 6 years, the EC has invested to extend the European eInfrastructure technology and European eInfrastructure (and particularly Grid) operational and organisational principles to a number of regions in the world, and reinforcing the close collaboration and exchange of know-how with similar technologies in other areas. A number of different collaboration models have thus been established between Europe and the rest of the world, while the projects implementing these collaborations have had impacts typically focused on their regions. The CHAIN project aims to coordinate and leverage these efforts and their results with a vision of a harmonised and optimised interaction model for eInfrastructure and specifically Grid interfaces between Europe and the rest of the world. The project will elaborate a strategy and define the instruments in order to ensure coordination and interoperation of the European Grid Infrastructures with other external e-Infrastructures. The CHAIN consortium, consisting of leading organisations in all the regions addressed by the project, will ensure global coverage, European leadership, and most efficient leveraging of results with respect to preceding regional initiatives. First, the project will define a coherent operational and organisational model, where a number of EU countries/regions will possibly act, in collaboration with EGI.eu, as bridges/gateways to other Regions/Continents. Further, the project will validate this model by supporting the extension and consolidation of worldwide virtual communities, which increasingly require distributed facilities (large instruments, distributed data and databases, digital repositories, etc.) across the regions for trans-continental research. Finally, the project will act as a worldwide policy-watch and coordination instrument, by exploring and proposing concrete steps for the coordination with other initiatives and studying the evolution of e-Infrastructures.