The planned European Spallation Source at Lund, Sweden, and the Institut Laue-Langevin at Grenoble, France, have reached agreement to carry out joint research projects in neutron science. The two organisations signed a memorandum of understanding on 26 September that will lead to collaboration over a wide range of projects. These will include the joint development of neutron-scattering instrumentation, beam-line components and neutron optics, and the development of detector technologies. The agreement also covers joint hosting and organisation of scientific and technical meetings. The €1.4-billion ESS will replace the ILL as Europe’s most powerful neutron source when it comes into operation.