Mulango Girls was started in 1955 by the African Inland Mission (AIM) in Wikililye sub-location in Kitui County, first as a primary school. It later was turned into a girls’ intermediate boarding school in 1959 and two years later, it was converted to a girls secondary school under Miss Joyce A Taylor, a Canadian missionary, who served for as its principal for 20 years.
The first cohort of Form Ones was admitted in 1963 with second and third streams being introduced three years later. Between 1978 to 1989, the school had an A-Level class studying arts subjects, including home science, dressmaking and cookery.