In order to share the effort of fast reactor development, a series of relevant agreements has been established among European countries involving research and development (R&D) and design organizations, utilities, and fuel cycle management. In particular, the R&D activities are divided among 11 working groups, which organize and share the technical work to be carried out. The European collaboration aimed at the best exploitation of resources and avoiding duplication of efforts seems to be the most powerful means of managing the transition to commercialization of fast breeder reactors.