In a land area of 5,196 square kilometers, the diocesan territory covers the civil districts of East Khasi Hills and Ri Bhai in the state of Meghalaya. Shillong is the biggest town in the diocese.
In the diocesan territory, the population is 1,170,000 at the end of 2017. Khasi, Garo, Karbi are the major ethnic tribal groups in the diocese.
Khasi, Pnar, Hindi, English, Assamese, Garo, Karbi, Tiwa and Nepali are the languages used in the diocesan territory.
In 1889, the Prefecture Apostolic of Assam was created with headquarters at Shillong, and was entrusted to the German Salvatorian Fathers. With the outbreak of World War I, the German Salvatorian Fathers were forced to return to their country and the Jesuits of Calcutta looked after Assam till it was entrusted to the Salesians of Don Bosco in 1921.
In 1934, the Diocese of Shillong was erected and Father Louis Mathias SDB was appointed as its first Bishop. Following his transfer to Madras, Bishop Stephen Fernando SDB of Krishnagar Diocese was transferred to Shillong as its second Bishop in 1935.
In 1951, the Diocese of Shillong was bifurcated and the Diocese of Dibrugarh was created. In 1964, the Diocese of Shillong was once again divided and a new Diocese of Tezpur was created. In 1969, Shillong Diocese was raised to the status of a Metropolitan See and a new Ecclesiastical Province of Shillong-Guwahati was created and Bishop Hubert D'Rosario SDB, was transferred from Dibrugarh to Shillong as its first Archbishop. The Archdiocese of Shillong-Guwahati was divided again in 1973 to form the Diocese of Tura. The next division of Shillong-Guwahati Archdiocese is the creation of Diphu Diocese in 1983. On September 23, 1990. Bishop Tarcisius Resto Phanrang SDB was appointed as auxiliary Bishop of Shillong-Guwahati. Further bifurcation of Shillong-Guwahati Archdiocese was made in 1992 with the creation of Guwahati Diocese. Archbishop Hubert D'Rosario SDB went to his eternal reward on Aug. 30, 1994. On Aug. 1, 1995, Bishop Tarcisius Phanrang was appointed Archbishop of Shillong.
Archbishop Resto Phanrang went to his eternal reward on May 5, 1999. At the death of Archbishop Tarcisius Resto Phanrang SDB, Father Michael Marbaniang was appointed as the Diocesan Administrator of the Archdiocese. On April 2, 2000, Father Dominic Jala SDB was ordained Archbishop of Shillong.
On April 2, 2006 Archbishop Lopez Quintana, the Apostolic Nun
The City is managed by Corporation. The villages and small towns are administered by elected local bodies called Panchayats and municipalities respectively.
The diocesan area is well connected in terms of transport infrastructure by roads. The nearest airport is in Guwahati city.
Rupees 18,274 (USD395 as of November 2009) is the per capita income in the territory of the archdiocese. Farming especially vegetables like potatoes, cauliflower are grown in the diocesan area. A few industries like cement factories are situated near the Assam border.
Government and private operators provide extensive telecommunication facilities in the diocesan area. The diocese is well connected by local cable TV networks.
70.9 per cent is the literacy rate in the diocesan territory.