Prem Tinsulanonda International School

The highest-fee and most internationally recognised school in Chiang Mai — a genuine outlier in the local market. A full IB World School with all four programs, including the rare Career-related Programme. Boarding and day school, ages 2.5–18, on a 100-acre campus in the Mae Rim hills north of the city. Graduates regularly place at Ivy League and top global universities. The campus is notably isolated — factor in the commute if you're not boarding. Parents are effusive — the campus and working farm, a standout arts programme, and a faculty many rate the best in the city — with that commute the main practical tradeoff. Like CMIS, students here reliably default to English with one another. The IB years are demanding and students work genuinely hard, but Prem graduates are among the most competitive for university admissions in the city.