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Founded in 1957 as a non-profit organisation under Sri Lankan law, the school was originally named The Colombo School for Overseas Children. It was located at Queen’s Street in Colombo Fort when the school first opened on 23 September 1957. The founders were from diplomatic missions (British High Commission, Burmese High Commission and Dutch Embassy) and the business community; this still reflects the school population today.

In September 1961, the school leased the premises known as “Rippleworth” at Turret Road (Dharmapala Mawatha) in Colombo 3. The younger children remained at the Fort while the older children moved to Rippleworth. In August 1963 the school in Fort had about 100 children, while the school at Rippleworth, known as the Upper School, had about 70 children. In 1967 the school gained accreditation by the International Schools Association in Geneva, Switzerland.

To cope with an increasing number of pupils, in 1971 the school relocated to 51 Muttiah Road in Colombo 2 (Rivington) until finally in 1983 the school was relocated to its present address Pelawatte, Battaramulla. During the same year, the school obtained accreditation by the International Baccalaureate (IB) Organisation as an IB World School fully capable of offering the IB Diploma Programme. In 1982, the school changed its name to Overseas Children’s School (OCS).

In 1990 the school received further accreditations from ECIS (European Council of International Schools) and MSA (Middle States Association of Colleges & Schools) and over the next five years opened its gymnasium and swimming pool. As the school developed, it became recognised by the US Office of Overseas Schools and has built close ties with the US Embassy, while maintaining links with other diplomatic missions. In 1996 the school took its present name, The Overseas School of Colombo. Continuing its campus development programme, the school built a new performing arts facility in 2005, renovated its primary and secondary libraries, and inaugurated a new, state-of-the-art sports facility in 2009.

The Overseas School of Colombo remains Sri Lanka’s oldest internationally accredited educational institution. It is the only school in Sri Lanka to offer the International Baccalaureate Programme from Pre-school to Grade 12. OSC is a multinational English-medium international school catering to the needs of the internationally mobile expatriate community and Sri Lankan students. At OSC we provide an educational setting that is focused on developing each student to achieve their full potential. That degree of personal excellence can only come with highly qualified teachers committed to the needs of all students on a campus which balances nature with state of the art technology, facilities and resources. OSC is a culturally diverse community with students, parents and staff working in harmony.


Queen's Street, Colombo - Home of the first OSC campus (1957 - 1967)

The Colombo School for Overseas Children was established at Queen’s Street in Colombo Fort by founders from diplomatic missions (British, Burmese, and the Dutch High Commissions) and the business community.

Some of our first students way back in the '60s at the second campus on Turret Road (Dharmapala Mawatha)
The School leased the ‘Rippleworth’ premises at Turret Road (Dharmapala Mawatha) in Colombo 03, which came to be known as the Upper School.

Boarders in the '60s
The School in Fort had 100 children, while the Upper School at Rippleworth had about 72 children.

International Schools Association
The School gained accreditation by the International Schools Association in Geneva, Switzerland.

A group of seniors at the Muttiah Road campus
The School relocated to 51, Muttiah Road in Colombo 02 (Rivington).

The Primary School at Coniston Place
The School was renamed Overseas Children’s School (OCS).

The new school campus in Pelawatte, Battaramulla
The school relocated to its current address in Pelawatte, Battaramulla. Situated on six acres of pristine land in Sri Lanka’s administrative capital, Sri Jayawardenapura Kotte, the new campus was designed by the legendary Sri Lankan architect Geoffrey Bawa. It stands as a next-to-nature facility, boasting all modern amenities.

IB World School
The School obtained accreditation by the International Baccalaureate (IB) Organisation as an IB World School, capable of offering the IB Diploma Programme.

Council of International Schools (formerly, European Council of International Schools)
The School received accreditation from ECIS (European Council of International Schools).

Middle States Association of Colleges and Schools
The School received accreditation from MSA (Middle States Association of Colleges and Schools).

The gymnasium was declared open.

  Swimming Pool
The swimming pool was opened to staff and students.

The Overseas School of Colombo (OSC)
The School took its present name – The Overseas School of Colombo.

A performance arts facility was built.

Week Without Walls: Experience Sri Lanka!
The School introduced its Week Without Walls (WWW) programme – now known as Experience Sri Lanka! Where for one whole week, the great outdoors is transformed into one big classroom!

Indoor Sports Complex
A new sports facility was inaugurated.

OSC’s Mother Tongue Programme
OSC’s Mother Tongue programme was first introduced, offering Hindi lessons to our students. The programme has now grown into a full-fledged offering of eight different languages including French, Hindi, Korean, Chinese, Slovene, German, Spanish and Swedish.

Unity in Adversity
Navigating the challenges of COVID-19, OSC pioneered a successful Distance Learning Plan, ensuring a seamless shift from physical to virtual classrooms. Embracing 'Unity in Adversity' as our motto during this challenging period, we led the way in Sri Lanka's virtual education landscape. Our swift and safe return to face-to-face learning showcased OSC's resilience and commitment to excellence.

Outdoor Basketball Court
The School’s outdoor basketball court was re-laid with a state-of-the-art, FIBA-approved, professional playing surface.

Secondary Science Lab
The Secondary and Middle School laboratories received a modern facelift, featuring a new layout for improved teacher-student interaction, upgraded equipment including a cutting-edge fume cabinet, enhanced air circulation, energy-efficient air conditioning, and safety-focused additions like power and gas cut-outs. Another stride in providing top-notch, state-of-the-art facilities for a dynamic learning environment at OSC.

OSC's Eco-Schools committee with the prestigious Green Flag
OSC made history as the first school in Sri Lanka to receive the prestigious Eco-Schools Green Flag Award from the Foundation for Environmental Education (FEE). Recognised for our unwavering commitment to sustainability and meeting global standards, OSC stands as a trailblazer in eco-conscious education, earning well-deserved international acclaim.

OSC Annual Report 2020/21: Our ‘A-Team’ Brings Its ‘A-Game’ to School
OSC clinched a Silver Award at the 36th Annual ARC Awards in New York for its 2020/21 Annual Report, themed Our ‘A-Team’ Brings Its ‘A-Game’ to School'. Competing in the 'Non-Profit Organisation' category, this prestigious recognition, known as the ‘Oscars’ of Annual Reports, marked OSC as the first-ever IB School globally to receive an ARC Award. The report set new standards in excellence, reaffirming OSC's commitment to outstanding communication in the global educational arena.

OSC's DEIJB team: Leading the charge toward a more inclusive future
OSC achieved a milestone by formalising its DEIJB (Diversity, Equity, Inclusivity, Justice and Belonging) policy, showcasing our commitment to diversity and inclusion. Our dual accreditation by CIS and MSA underscores our dedication to transparency and excellence, emphasising our commitment to global citizenship and intercultural learning through a strategic DEIJB agenda for justice, belonging, and anti-racism.

New Front Entrance and Security Complex
The completion of the New Front Entrance and Security Building Project marked a significant milestone. The Security Complex, with cutting-edge screening tools, ensures secure entry via a dedicated driveway. The Access Control System, commissioned across spaces, guarantees safety, and unique Turnstile Gates at main entrances permit authorised entry. The comprehensive Perimeter CCTV System covers the school perimeter for vigilant monitoring. These enhancements symbolise our ongoing commitment to safety and a welcoming school environment.