International School of Brussels

ISB is the largest international school in Belgium and the default for many embassy, EU and corporate families. A 40-acre campus in Watermael-Boitsfort, around 1,350 students from 70-plus nationalities, full IB continuum plus AP.

Founded in 1951, ISB has the resources and breadth that smaller schools in Brussels cannot match. Sports, arts, STEM, learning support, university counselling. Diploma and AP run side by side, which is unusual and useful for families weighing US-style admissions against the IB.

Parent voice is consistently warm on inclusiveness, the active Family Association, and how quickly new arrivals settle. Many families cite the sheer scale of campus and range of activities as the deciding factor over BSB or BEPS.

Big means big. Children who thrive on choice and a wide social pool do well. Children who prefer to be known by name in a small setting can find it impersonal in the early days. Fees are at the top of the market, and the commute from the European quarter is a real journey.

• One of the long-established American-flavoured Brussels options, set on the Watermael-Boitsfort campus and routinely paired with British School of Brussels and St John's in expat school searches.
• Parents describe ISB as "a bit more of a party reputation, especially for secondary schoolers" relative to BSB, which other parents frame as more academic.
• Some parents say ISB has been doing the IB longer than BSB and produces strong results, but flag that extracurriculars are billed on top of fees and that a sizeable share of the student body is wealthy Belgians.
• A non-licensed teacher said they were hired through Schrole, which signals that the school does take staff without traditional state certification.
• Cohort and demographics: one alumnus describes a four-year stay that exposed them to many nationalities; another parent reports their family found ISB a good fit on income.
• A 2024 family complaint described bedbug bites on a school field trip, raising questions about boarding and trip safeguarding rather than day-to-day operations.