The school offered students an international education from Nursery to Year 13 (Kindergarten to grade 12). The school was divided into three phases : Infants (nursery and Key Stage 1), Junior / Middle School (Key Stage 2 and 3) and High School (Key Stages 4 and 5). The school followed the British Curriculum (See Education in England) to Year 11 where students took IGCSE; students in Senior High School undertook a university preparation programme. Students who successfully completed Year 13 (grade 12) were awarded with a High School Diploma. St. John's International School was a founding member of the International School Association of Thailand (ISAT). It was also the first school in Thailand to be designated under the Safe School Community International Accreditation Programme (SSCIAP) by the Safe Communities Foundation New Zealand.