Itanagar has been the capital of Arunachal Pradesh in the North East. Erected on Dec. 07, 2005, it comprises of the civil districts: Tawang, West Kameng, East Kameng, Papum Pare, Upper Subansiri, Lower Subansiri, Kurung Kamay, West Siang, East Siang, and Upper Siang.

The new diocese of Itanagar, bifurcated from Tezpur has an area of 52,288 sq. kms. With 1, 01,689 Catholics, 11 parishes, 3 diocesan priests, 22 religious priests, 10 religious brothers and 40 religious sisters. The parish of St. Joseph in Itanagar is the Cathedral of the new diocese and St. Joseph is the Patron of the diocese.

The first Bishop of Itanagar, Bishop John Thomas Kattrukudiyil, was born in 1948, ordained priest in 1975 and was appointed Bishop of Diphu in 1994. Bishop John has a Licentiate in Sacred Scripture and a Doctorate in Biblical Theology. He was for many years a formator in Seminaries and was also Rector of the regional Major Seminary in Shillong.