Mission Viejo High School was the first high school in Orange County that was granted full affiliation with the prestigious International Baccalaureate Program in the fall of 1984. is a comprehensive program for academically talented and highly motivated students sponsored and administered by the International Baccalaureate Organization. The International Baccalaureate Diploma is awarded to students who meet the following requirements: specific course work in six academic disciplines, with students completing classes and writing external examinations in all six areas: English, Foreign Language, Study of Humanity, Experimental Sciences, Mathematics, and one additional selection. The International Baccalaureate Program has been validated by the Ministries of Education in more than 40 countries throughout the world. The International Baccalaureate Diploma and individual certificates are recognized for admission and advanced standing in the United States and throughout the world. Mission Viejo High School students received 40 full diplomas in 2013-14. The three year IB exam pass rate is 92%.
Candidates who successfully complete all the requirements of the IB Diploma Programme and one or more of the following combinations are eligible to receive a bilingual diploma: two Group 1 subjects (of different languages), a Group 3 or 4 subject taken in a language other than the candidate's Group 1 language, or an Extended Essay in a Group 3 or Group 4 subject written in a language other than the candidate's Group 1 language.  IB certificates are issued to indicate completion of diploma courses and exams for non-diploma candidate students.