The ILL is governed by its Associates, the founding countries:

• France, via the Commissariat à l’Energie Atomique (CEA) and the Centre National de la Recherche Scientifique (CNRS)
• Germany, via the Forschungszentrum Jülich (FZJ)
• The United Kingdom, via the Science and Technology Facilities Council (STFC)

in association with its Scientific Member countries (listed below by chronological order of accession):

• Spain: Ministerio de Educación y Ciencia (MEC)
• Switzerland: State Secretariat for Education and Research
• Austria: Austrian Academy of Science (*)
• Italy: Istituto Nazionale per la Fisica della Materia (INFM)/Consiglio Nazionale delle Ricerche (CNR)
• the Czech Republic: Charles University of Prague (*)
• Sweden: Swedish Research Council (**)
• Hungary: Hungarian Academy of Sciences (*)
• Belgium: Belspo (**)
• Slovakia: the Comenius University in Bratislava (*)
• Poland: the Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences in Kraków (**)
• India: the Bhabha Atomic Research Centre in Mumbai

(*) These four countries form the Central European Neutron Initiative (CENI).

(**) These three countries form the Belgian-Polish-Swedish Neutron Initiative Consortium (BELPOLSWENI).