eInfrastructure in Europe has reached a mature state where the GÉANT network forms a backbone on top of which a distributed computing infrastructure – the Grid – provides processing and storage services for eScience research. The South-East European eInfrastructure initiatives are committed to ensuring equal participation of the less-resourced countries of the region in European trends. SEEREN initiative has established a regional network and its GÉANT connection and the SEE-GRID initiative the regional Grid. Hereby proposed SEE-GRID-SCI will leverage the SEE eInfrastructure to enable new scientific collaborations among SEE user communities. SEE-GRID-SCI will stimulate widespread integrated eInfrastructure uptake by new cross-border user groups extending over the region, fostering collaboration and providing advanced capabilities to more researchers, with an emphasis on strategic groups in seismology, meteorology and environmental protection. The initiative thus aims to have a catalytic and structuring effect on a variety of user communities that currently do not directly benefit from the available eInfrastructures. In parallel, it will enlarge the regional eInfrastructure to cater for demands of the communities: a number of new Grid clusters and countries will be added, engaging a wider range of players and expanding the provider pool. Finally, SEE-GRID-SCI will help mature and stabilise the National Grid Initiatives in the region, allowing them to join the new era of longer-term sustainable Grid infrastructure in Europe. In this context, SEE-GRID-SCI will aim to attract political and financial support for materializing the eInfrastructure vision. In longer term, SEE-GRID-SCI aspires to contribute to the stabilisation and development of South-East Europe, by easing the digital divide and stimulating eInfrastructure development and adoption by new user communities, thus enabling collaborative high-quality research across a spectrum of scientific fields.