Slovenia joined the CERN programme soon after becoming an independent state, participating in experiments at LEAR and LEP (DELPHI). In 1991, a Co-operation Agreement between CERN and the Executive Council of the Assembly of the Republic of Slovenia concerning the further development of scientific and technical co-operation in the research projects of CERN was signed. In 2009, Slovenia applied to become a Member State of CERN.
The Slovenian interaction with CERN has been very effective, in view of the small size of its HEP community. Slovenia participates in ATLAS, with the development and production of low-mass power and signal cables for the Silicon Tracker, a share in the Common Fund and testing equipment on the reactor in Ljubljana.
Since 4 July 2017, Slovenia is an Associate Member in the pre-stage to Membership of CERN.