Lithuania became an Associate Member State on 8 January 2018.
In 2004, a Co-operation Agreement between CERN and the government of the Republic of Lithuania concerning the further development of scientific and technical co-operation in high-energy physics was signed. A Protocol to this agreement concerning the participation of universities and scientific institutions from the Republic of Lithuania in the high-energy particle physics experiments at CERN was signed in 2005 and a Memorandum of Understanding (MoU) for the construction of CMS was signed in 2007. Lithuania has been instrumental in the database development at CERN for CMS data mining and data quality analysis, as an in-kind contribution of Lithuania.
Lithuania actively promoted the BalticGrid in 2005. The Grid activities centered in Vilnius were based on a cluster with 150 CPUs of which 100000 CPU hours were allocated to CMS in 2007. Lithuania participates actively in RD39 and RD50, and in the CERN Summer Student Programme in order to strengthen their particle physics teams.