From CERN press release dated 17 July 2016:

On 17 July 2016, Romania became the twenty-second Member State of CERN.

Contacts between CERN and Romania began back in 1991, when a scientific and technical cooperation agreement was signed, establishing the legal framework for later developments.

Aspiring to become a full-fledged Member State and thus to contribute fully also to the governance of the Laboratory, Romania submitted its formal application to join the Organization in April 2008. The Agreement granting Romania the status of Candidate for Accession came into force on 12 November 2010.

Romania's scientific community at CERN has grown over the years and currently numbers around a hundred visiting scientists. Romania has particularly strong presence in the LHC experiments ATLAS, ALICE and LHCb. Romanian researchers and engineers also work at DIRAC and n_TOF at the Proton Synchrotron (PS), on the NA62 experiment at the Super Proton Synchrotron (SPS), and at the ISOLDE facility. Romania is also active in the Worldwide LHC Computing Grid.

Read the press release here.