IB Continuum vs IB Diploma: why the distinction matters
Many schools in Portugal advertise "IB" — but most offer only the Diploma Programme, a two-year qualification for students aged 16–18. A full IB Continuum school delivers three connected programmes across your child's entire school life:
Oeiras International School — top-ranked by IB results
Founded in 2010, Oeiras International School occupies a historic Portuguese quinta — an estate dating to the 17th century — surrounded by forest, a river, and open green space. The natural setting is integral to how the school approaches learning, not merely decorative. There are animals on campus, and younger children from the junior campus regularly visit the grounds for sports and outdoor activities.
In 2025, the school recorded an average IB Diploma score of 36 out of 45 — placing it well above the global IB average of approximately 30–31, and among the top-performing IB schools in Europe. The school publishes its results transparently.
Oeiras is entirely non-profit, governed by a charitable parent foundation. All tuition fees are reinvested into the school — no shareholders, no commercial operators. Class sizes are deliberately small: a maximum of 18 students, with an average of 16. This combination of strong results, small classes, and non-profit governance is rare anywhere in Portugal.
Best for
Families prioritising strong IB results, small classes, a nature-integrated campus, and a school governed entirely in the interests of its students.
St. Dominic's International School
One of the oldest international schools in Portugal, St. Dominic's has been operating since 1955. Seven decades of continuous operation mean the IB framework is deeply embedded in the school's culture and teaching practice. The school offers the full IB Continuum and publishes consistent Diploma results year on year — an average of 32 out of 45 with a 91% pass rate, both above the global benchmark.
For families who value institutional stability and a long, proven IB track record, St. Dominic's is the most established option in the Lisbon area.
Best for
Families who value institutional stability, a long IB track record, and consistently above-average results in a well-established academic environment.
International Sharing School — Taguspark
published
Founded in 2017 and designed around contemporary IB pedagogy, ISS Taguspark sits in the Taguspark technology campus in Porto Salvo — conveniently located between Lisbon, Oeiras, and Cascais, with easy access from the A5 motorway. The campus is spacious and modern, with one of the broadest extracurricular programmes of any international school in the Lisbon area.
The school offers the full IB Continuum from age 3 to 18, and also runs summer camps open to non-enrolled children — a practical way for families to test the environment before committing. One note: the school does not publicly disclose its IB Diploma results, which makes academic benchmarking harder than with the other two schools in this guide.
Best for
Families relocating to the Oeiras, Cascais, or Sintra corridor who want a full IB continuum with a wide extracurricular offer and a modern campus.
Side-by-side comparison
| Criterion | Oeiras Int'l | St. Dominic's | ISS Taguspark |
|---|---|---|---|
| IB avg score (2025) | 36 / 45 | 32 / 45 | Not published |
| Full IB Continuum | ✓ PYP · MYP · DP | ✓ PYP · MYP · DP | ✓ PYP · MYP · DP |
| Founded | 2010 | 1955 | 2017 |
| Class size | Max 18 · avg 16 | 16–20 students | Up to 25 |
| Non-profit | ✓ Parent foundation | — | — |
| Campus character | Historic quinta · forest · river | Established campus | Modern · spacious |
| Location | Oeiras | Lisbon / Cascais corridor | Porto Salvo · A5 |
| Waiting list | Yes — apply early | — | — |
| Fees from | €13,980/yr | €12,100/yr | €11,790/yr |
How to choose the right IB school in Lisbon
The right school depends on what your family prioritises. A few questions worth asking before shortlisting:
How important are university placement outcomes? A score of 36 vs 32 can meaningfully affect admissions to competitive institutions. If top-tier university results are a priority, Oeiras leads by a clear margin.
Does the campus environment matter? Oeiras is genuinely unlike any other school in the area — forest, animals, a river, and a historic estate. ISS Taguspark offers a modern, spacious alternative. St. Dominic's brings decades of accumulated character.
How long will you be in Portugal? For shorter stays, location and commute time may outweigh other factors. ISS Taguspark's position on the A5 makes it the most accessible from a wide area.
Does class size matter to you? Oeiras caps classes at 18, with an average of 16 — significantly below ISS Taguspark's maximum of 25.