There are about 46,000 Catholics in the country, 70% of whom were born abroad. The country is divided into three Church districts – the Diocese of Oslo and the prelatures of Trondheim and Tromsø and 32 parishes.
The Bishop of Oslo participates in the Scandinavian Bishops Conference.
The subsequent Christianisation took several hundred years. Largely the work of Anglo Saxon missionaries, the Norwegian Church has been considered the only daughter of English Catholicism. Cardinal Nicholas Breakspear, later Adrian IV, established a church province in 1152, the archdiocese of Nidaros (Trondheim). The prosperous years of the High Middle Ages were followed by decline for Church and nation alike, although Norwegian Catholicism retained much of its vitality.
Many traditions from the Catholic Middle Ages continued for centuries more. In the late 18th century and into the 19th century, a strict and puritan interpretation of the Lutheran faith, inspired by the preacher Hans Nielsen Hauge, spread through Norway, and popular religious practices turned more purely Lutheran.
The Catholic Church per se, however, was not allowed to operate in Norway between 1537 and 1843, and throughout most of this period, Catholic priests faced execution. In the late 16th century, a few incidents of crypto-Catholicism occurred within the Church of Norway. The Roman Catholic faith survived in remote parts of the Kingdom until approximately 1700. Christiania (Oslo) had an illegal but tolerated Catholic congregation in the 1790s. In 1843 the Norwegian Parliament passed a religious tolerance act providing for limited religious freedom and allowing for legal non-Lutheran public religious services for the first time since the Reformation.
In 1956, the final constitutional restriction on Catholics was lifted when Jesuits were allowed to enter the country for the first time since the Reformation, though it is known that at least one Jesuit - Xavier Rénom de la Baume - was killed in action with French Alpine forces during the Battles of Narvik.
Religious sisters working in hospitals and schools did much to overcome popular suspicions about Catholics. Sigrid Undset, a Catholic convert, and the Rev. Hallvard Rieber-Mohn, O.P., also contributed to this. Protestants and Catholics were brought closer together in firm opposition to the Quisling regime during the German occupation (1940-1945).
At first, the immigrants came from Germany, The Netherlands and France. Immigration from Chile, the Philippines and from a wide range of other countries began in the 1970s. This development has further increased in the last few years with economic immigrants from Poland and Lithuania. The official number of Catholics, however, decreased slightly in 2004. This is because the Norwegian state demands a person's social security number (fødsels-og personnummer) in order to grant the per capita subsidy. The real number of Roman Catholics in Norway is possibly as much as twice the official number of 50,000.