IIn 1972, with the conviction that Athens needed a truly International school The Hellenic International School in Athens (HIS) was founded, absorbing the English-speaking Ursuline Primary School. HIS offered American and British programmes to international students from all over Athens and developed a high reputation for academics. A boarding school aimed mainly at expatriate families in the Middle East was established by the TASIS organization (The American School in Switzerland) in 1979, subsequently merging with HIS to form TASIS Hellenic International School. The addition of as many as 160 students from abroad gave TASIS Hellenic an even stronger international profile. The boarding programme later was established in Varibobi at the charming "Auberge", and then at a traditional villa in Kifissia. When the boarding school closed in 2005, the villa was adapted for the use of young students, and Melina’s Kindergarten was born. The great success of this programme led to the establishment of Melina’s Junior Kindergarten for children aged two and three.

In 1998, following many years of offering first GCE O-levels and then IGCSE, as well as GCE A-levels, the school switched from the British programme to the International Baccalaureate Diploma Programme. It was felt that this change better served the needs of our students, helping them prepare for the 21st century world.

When our sister school, the International School of Larissa, was founded in 2003, the name of our school was changed to the International School of Athens to better reflect the nature of the school and to create a unified identity for the two schools.