Model United Nations (MUN) is an program in which students can learn about diplomacy, international relations, and the United Nations through educational simulation and academic competition. Tustin High School has been participating in MUN since 1992. THSMUN hosts one of the largest Model United Nations conferences for high school students in Southern California every November, run completely by high school students. Tustin High School also boasts four a-g approved grade level honors classes for MUN students in which they learn about global issues, cultural geography, American foreign policy, and comparative government.