Founded in 1998 in Bangkok, and 1995 in Khao Yai, Thailand, St. Stephen's International School (SIS) joined FOBISIA in 2006. 

The school follows a British type curriculum, and offers the International General Certificate of Secondary Education (IGCSE) at both campuses, and A Levels at the Bangkok campus. 

St. Stephen's International School is accredited by an approved inspectorate.