For many years, CERN has operated a trans-national Fellowship programme, offering scientists and engineers challenging opportunities in particle physics research, and in related fields of physics and technology. CERN secured COFUND grants in 2008, 2010 and 2011. They offer CERN a timely opportunity to enhance the mobility element of this programme without nationality limitations. The 2012 Call comes at a time when the start-up of the Large Hadron Collider has made CERN one of the most exciting places to work for the global physics and technology community.Applicants will propose their own research projects. Selection will be based on the scientific potential of the proposal, and on the demonstrated excellence of the candidate. Working on frontier research and technology projects and profiting from the unique facilities available at CERN, the co-funded Fellows will deepen their knowledge in their own field and acquire international visibility and reputation. They will broaden their skills using the numerous training opportunities and through their exposure to an interdisciplinary and multi-national environment. Inter-sectoral skills will be fostered through CERN’s industrial collaborations and technology transfer projects.Employment conditions will be improved by offering three-year appointments rather than the standard two-year terms of CERN Fellows. At least two of these three years will be spent at CERN. We consider this provision to be justified by the size of the Laboratory, the diversity of the research and training opportunities, and by the uniqueness of CERN’s facilities. However, mobility will be enhanced through the opportunity to spend up to one third of the Fellowship in external institutions, including industrial laboratories, on secondment from CERN under the conditions of the full employment contract. These improvements, enabled by the COFUND action, will further increase the competitiveness of CERN’s Fellowship Programme.