Proposals for new accelerators at CERN were under consideration from the late 1950s, with the main contenders being Intersecting Storage Rings (ISR) for the exisiting PS and construction of a new larger synchrotron.
In 1963 a Working Party of ECFA (European Committee for Future Accelerators) recommended the construction of both the ISR and the 300 GeV Proton Synchrotron.
An electron model was built at CERN to check some of the basic features of this idea and this model, called CESAR, came into operation in 1963.
In September 1965 France signed an agreement to provide about forty hectares of land, adjacent to the CERN site located on the Swiss border, for the construction of the ISR. In December, the Council approved the ISR project, and continued study of the 300 GeV project (SPS).
In 1966 the ISR division was created and K. Johnsen was appointed as Division leader. Its main task was the design and construction of the ISR and also a technical study of the 300 GeV accelerator (SPS). In the same year, the Council approved proposals by the Director-General for a reorganization of the structure of CERN and 7 new departments were formed. The ISR division was integrated in the ISR Construction Department directed by K. Johnsen.
In 1967 the Accelerators Research Division (AR) was transferred to the ISR division.
In 1971 the ISR machine first came into operation with the PS as the injector. In 1971, following approval for the construction of a second Laboratory adjoining the existing site, divisions were divided between two administrative units, Laboratory I and Laboratory II. ISR Department became part of Laboratory I.
In 1976 the two Laboratories were united. The departmental structure ceased and ISR division remained.
In 1982 Council approved the proposal to dissolve the ISR division.