St. Mbaaga’s seminary is a diocesan major seminary belonging to Kampala Archdiocese. The Archbishop of Kampala, His Grace Dr. Cyprian Kizito Lwanga is the supreme head of this seminary and he is the one responsible for its staffing and general welfare and in drawing the regulations that govern it. Although St. Mbaaga’s is a diocesan major seminary, but aims with all means the better provision for the “solid training of the students” (OT. 7) “to make them true shepherds of souls after the example of Our Lord Jesus Christ, teacher, priest and shepherd” (OT. 4). St. Mbaaga’s major seminary is the only diocesan major seminary in the whole of the AMECEA region.

The history of St. Mbaaga’s Major Seminary goes as far back as 1931. It was in that year that the Mill Hill missionaries opened a major seminary on these premises for what was then Kampala diocese which was under their care. During its thirty six years of existence it produced abundant fruits for the church in this country. Many priests trained here during that period are still with us. Among them are seven Bishops:

• His Eminence Maurice Cardinal Otunga (R.I.P) former Archbishop of Nairobi.
• His Grace Archbishop James Odongo, Archbishop of Tororo
• His Lordship Bishop Joseph Mukwaya (R.I.P), Emeritus Bishop of Kiyinda Mityana
• His Lordship Bishop Erasmus Wandera, Bishop of Soroti
• His Lordship Bishop Joseph Oyanga, Emeritus Bishop of Lira
• His Lordship Bishop Denis Kiwanuka, Bishop of Kotido
• His Lordship Bishop Phillip Sulumeti, Bishop of Kakamega, Kenya.