International School of Brussels

In Brief

ISB is the right call for families who want genuine inclusion alongside strong IB results, and who value the stability that comes from being the oldest and only truly independent not-for-profit English school in Brussels. The campus at Kattenberg is large and green, though it is less convenient from the city centre than some alternatives.

ISB has been operating since 1951 - it predates BSB by nearly two decades - and is still the only not-for-profit international school in Brussels unaffiliated with a religion, nationality, or corporate group. That governance structure gives it a different character: a self-perpetuating Board of Trustees focused on the school's long-term mission rather than returns. The campus at Kattenberg 19 in Watermael-Boitsfort sits in a protected natural zone on the edge of the Sonian Forest; the setting is calm and green, and the facilities include a high school building opened in 2013 that is widely praised for its design.

The curriculum is built around ISB's own Common Ground framework, with the IB Diploma as the culmination. Results average 35 points with a 97% pass rate; university destinations include Brown, Duke, MIT, UCL, and most leading European universities. The school's learning support programme is considered a model for inclusion in the international school sector - students with diagnosed learning disabilities are integrated into mainstream classes with structured support, and many families with children who have specific needs choose ISB precisely for this reason.

Fees run higher than most families expect: EUR 49,715 for Grades 10-12 in 2025-26, with a EUR 2,000 application fee on entry. Those fees buy access to a school with 60+ co-curricular activities, athletics, performing arts, and genuinely small advisory groups. A new Director takes over in August 2026 following James MacDonald's six-year tenure - worth asking at admissions how the transition is being managed and what the incoming Director's priorities are.