IB Diploma Programme By Mark Twain IS 26 November 200826 November 2008 Mark Twain International School is authorized to offer the IB Diploma Programme for students grades 11-12, preparing for the International Baccalaureate. Previous First performance at the Cultural Centre of the Romanian Mission to the United Nations 5 May 2000 Next Mark Twain International School becomes an IB World School 20 March 2006