In 1939, the school was moved to a new site at Mangu Village on twenty-two acres of land and because of accessibility it became known as Mangu High School.However, the Marianist Brothers introduced an Aviation programme in Mangu High School and there was an urgent need for expansion. Therefore, to create room for the Aviation programme, the Board of Governors decided to purchase a new site for the school. They acquired 214 acres six kilometres from Thika Town along the Thika-Nairobi Highway. In 1972 the Marianist Brothers moved Mangu High School to its current site. The school was to be put up in three phases. Mang’u high school was the first to introduce aviation as an examinable subject in the country School nameAccording to Bro. Ken Thompson who taught English for 15 years at Mangu High School, "mangu" is a Maasai word meaning "thats not me you smell." Bro. Ken said: "When the Maasai hunted lions in the tall grass, they would shout "mangu, mangu" to inform their fellow hunters of the situation!"The school is also known as "Dayton" (although very few students are actually aware of this) because of the schools association with University of Dayton, a Catholic university founded by the Society of Mary (the Marianists) in 1850 in Dayton, Ohio, United States. AlumniMangu High School is a school that has made tremendous contribution to Kenyas history. The school boasts of a high profile of many successful alumni among them politicians, lawyers, businessmen, clergymen, scientists, engineers, doctors and pilots. Among the high profile politicians who studied at Mangu High School are President Mwai Kibaki who attained the maximum possible score, former Vice-President Moody Awori, Cabinet ministers George Saitoti who was also a former vice president, John Michuki who also met President Mwai Kibaki at Mangu and is a former school captain. Other cabinet ministers are Dr Mukhisa Kituyi, Kipruto Arap Kirwa, Cyrus Jirongo and the late Tom Mboya who was one of Kenyas principal leaders that agitated for independence plus other members of parliament. Other notable alumni include Cardinal Maurice Michael Otunga, Archbishop Ndingi Mwana Nzeki, Archbishop John Njenga who also met Mwai Kibaki and Moody Awori at Mangu and says he taught Hon. Awori catechism. Others are Bishop Antony Muheria, Josphat Konzolo former director NSSF (National Social Security Fund) and Dr. Joshua Noreh who performed Kenyas first Invitro-fertilization.In recent times the school has continued to produce great achievers, some of whom have been ranked in the top ten nationally in the KCSE exams. Past students have been admitted into top schools in the US, UK and Australia including Yale and Harvard.Facilities The first phase of construction was completed in 1972 and all the 253 students moved in. After that, very little has been done to complete the second phase and of course nothing for the third phase, yet the student population is already in the third phase.The school has got a swimming pool,fields which are to stardards,buses which enable transport to be efficient enough, a mordern library,a block of labolatories including aviation laboratory,a chapel , staff quaters,a mordern staffroom and other facilities.