COMET was a response by the European Commission and the European radioecology community to the need to ensure the sustainability of radioecologial research in Europe. Through COMET, the ALLIANCE developed stronger ties with the wider European radiation protection community and the international radiological sciences and ecotoxicology communities. The trans-national structure developed will be capable of ensuring appropriate governance of radioecology research to meet the challenges identified within the radioecology strategic research agenda. sThrough COMET, the ALLIANCE has positioned itself as a strong component of the Horizon 2020 Radiation Protection Federating Association. Our scientific strategy was to structure radioecological research in the most effective way, through the further development of the Radioecology SRA and to develop mechanisms of joint programming and implementation. The research activities advanced knowledge and expertise in transfer, exposure and effect assessment through innovative multidisciplinary research. We have strengthened collaboration between the radioecology and (post)-emergency and low-dose research communities. The development of future common research lines and a Joint Programme of Activities and Implementation Plan between NERIS, MELODI and the ALLIANCE will increase efficiency, leading to the optimised use of research funds and infrastructure, and a more holistic approach to research. COMET activities have been effectively disseminated and E&T packages have been developed to maintain and enhance professional competence.