The DULIA (Deep Underground Lab Integrating Activity) project aims to integrate the four operating European deep underground laboratories (LSM, LNGS, LSC and BUL) into a world-class distributed interdisciplinary and intersectoral infrastructure. Europe has for many years been the world-leader in deep underground science thanks to the capabilities of its four laboratories. Deep underground science is now growing, both in the scale and variety of the projects being proposed. Presently, the European deep underground laboratory host experiments from fundamental physics (neutrino, dark matter, nuclear physics, particule physics, astroparticule), biology, astro-biology, environmental sciences (climat, effect of human activity, oceanography,...), geophysics, microelectronics, among others. There is international competition for this growth however, with major underground science facilities now being operated in the US, Canada, Japan and elsewhere. The integrating activities of DULIA will secure and enhance Europe’s global leadership in the deep underground science field, making the European laboratories better, stronger and more impactful by working together rather than separately. All together the four laboratories will be a very attractive and unique world-class platform. It willl allow to avoid duplication of experiments and R&D as well as to provide a better service. DULIA will do this through the development of common procedures, the common coordination of laboratory space and support services, the sharing and common development of scientific, technical and operational expertise, and the promotion of the opportunities and services provided by the European laboratories to a wider range of science users. The DULIA project will achieve this through 1) Networking activities: facilitating efficient and effective sharing of information, procedures and resources, and promoting collaborative discussion of European underground science and science support strategies, 2) Transnational Access: promoting and supporting access to the four laboratories for new scientific, industrial and public sector users, and 3) Joint Research Activities: enabling the development of instruments and facilities highly relevant to deep underground science to provide better services to science users. The DULIA project’s activities will ensure that Europe continues to play a leading role in this important and exciting field. It will allow also to promote cooperation with other shallow underground laboratories in Europe and with the other deep undergorund laboratory in the world.