1960-1969

The Inter-Community School Zurich was founded on March 18, 1960, at a meeting at the Hotel Carlton Elite between the American, Australian, British and Canadian communities of Zurich.^[4] The school enrolled 84 students aged 4–13 during its first semester at the Hotel Rigiblick. There were five staff members employed at the time as well as the founder Gerald Atkinson and his wife.

In May 1961, ICS signed a lease with the city of Zurich for the rental of a lakeside villa (which in the 1930s had been renovated for use by Prince Paul of Yugoslavia)^[5] In September of that year, ICS began its second year of operation in the new villa with 160 students enrolled.

By 1967, there were 200 students enrolled from kindergarten to seventh grade with two classes per grade. Rooms were in short supply, therefore facility was found in Regensdorf. Shortly thereafter, the upper primary classes were moved to Regensdorf, while the lower primary classes remained in the lakeside villa on Seefeldquai. The search for one facility to house the entire school was now underway.

The founder of ICS Gerald Atkinson relinquished his ownership of the school in 1968, to facilitate the process of ICS gaining the legal non-profit foundation status. This non-profit foundation status would make it easier to raise funds for the purchasing of a new building. On August 1, 1968, the Foundation of The Inter-Community School was established under the Swiss Civil Code.

1970-1986

In early 1970 the municipality of Dübendorf, a suburb near Zurich, had just completed the construction of a new primary school, but only required half of the rooms. ICS was offered the use of the other half of the building for one year, while another more permanent location was sought. In April 1970, the lower primary classes moved out of the lakeside villa in Zurich to the new temporary facility in Dübendorf. The upper primary classes remained in Regensdorf during this period.

At the same time, the board of trustees had found a farmer in Zumikon who was willing to sell ICS some of his land. The contract for the purchase was signed in November 1970. After receiving two major loans from Credit Suisse and the Union Bank of Switzerland, ICS was ready to build its own facility. Construction began in November 1971 and was completed in December 1972. When the winter term began in 1973, the entire school was under one roof - this was the Primary School building. 270 students were now enrolled at ICS. In 1977 additional land was purchased, and extensions to the Primary School building were done in 1979 and 1982. Shortly thereafter in 1985, a library and kindergarten were built.

The 1974 'Brink Report' by the Board of Trustees formulated plans for the development of a secondary school at ICS. The first pavilion was erected in 1987 as the first secondary school classroom.