OIST encourages applications from Japan and other non-English speaking countries. Students not yet sufficiently confident in English may take part in an intensive immersion program in an English-speaking country prior to beginning their studies at OIST. Once at OIST, second language speakers of English can continue to improve their English in free classes taught by experienced, full-time professional English as a Foreign Language instructors. Students' family members can also attend these classes at no charge.

Though located in Japan, OIST is an international graduate university where all education and research are done in English. Japanese language ability is not required. However, living in Okinawa is a precious opportunity to enrich one’s life by learning the language and culture of Japan. OIST's full-time professional Japanese as a Foreign Language instructors teach several levels of classes to accommodate the needs of OIST students, employees, and their family members, at no cost to participants.

Students concerned with their proficiency in English in a laboratory setting, or those who lack preliminary experience in a laboratory environment, may apply to start early at OIST within its Gap Program.