They spread Christianity and baptized many converts. Catechists were also trained who helped in the spread of Christianity for example, in Uganda by 1911 many people had been converted and many cathedrals and churches were built like the Kikuyu churches (Charismatic Arathi or spirit churches.)
African religious beliefs, culture and traditions were despised and demoralized for example the birth and murder of twins, human sacrifice.
They established hospitals and clinics which offered modern medicine plus research in tropical diseases like malaria, small pox, yellow fever and sleeping sickness which had claimed many lives. For example Dr Albert Cook built Mengo hospital.
They introduced the European system of management and styles of dress and architecture which have been adopted by many people in East Africa today.
They put to an end the inter-tribal or inter-village wars and established a stable and peaceful society under one faithful leader (centralization).
They studied African languages and translated the Bible into various languages. For example Kraft translated the New Testament of the Bible into Swahili, Bishop Edward Steere based in Zanzibar learnt and studied Swahili and translated books from English to Swahili, published the New Testament and the entire Bible in 1891.
They established printing presses like Marianum press and published newspapers.
They opened up primary and secondary schools as well as training collages for teachers and trade schools for craftsmen e.g. Kisubi Vocational School, Kiteredde Brothers in Masaka. In the technical schools, carpentry and brick laying skills were obtained.
A new class of elite emerged. Africans educated mainly in English and French emerged, these later served as doctors, lawyers, clerks, teachers, catechists, agriculturalists and priests who played a great role of spreading Christianity. For example, in 1890, Africans were ordained as priests of the University Mission to Central Africa in Tanganyika.
They paved way for the improvement of agriculture through establishing experimental farms and plantations where new crops, better methods of farming and equipment were introduced for example cotton was introduced by Kenneth Boroup in 1903 and Africans were taught how to use a plough and how to grow coffee.
Missionaries improved communication and transport which in turn led to the opening up of the hinterland of Africa. The building of strong boats and ships gave Europeans courage to travel far from home.
Missionaries destroyed local industries like craft industry e.g. blacksmiths, pottery work were all destroyed and replaced with European products e.g. manufactured items like cups, saucepans, etc.
They contributed to the rise of nationalism. This was made possible through education where the African elite emerged and started demanding for independence e.g. Tom Mboya, Obote, Nyerere, and Kenyatta.
They fought slave trade which was later abolished and equality and liberty for all was encouraged in East Africa.
Mission stations were developed in towns like Rabai missionary station near Mombasa in 1846 Bagamoyo, Tabora, etc.