Around the year 1600, the Salzburg archiepiscopal dominion of Arnsdorf belonged to the few Catholic "islands" in a largely Protestant region. Its administrator Matthäus Häring held office in the grand Langeggerhof. When his daughter was taken seriously ill in 1604, he vowed before a picture of the Virgin Mary to build a chapel if his child should recover. The following year he fulfilled his pledge and put the image of Mary on display for public veneration. Soon it would be visited regularly by pilgrims.
At the time of the counter-reformation, the Langegger pilgrimage was supported by the Habsburgs. Important personages showed their reverence to the pilgrimage by offering donations, not least to demonstrate their loyalty to the imperial family as well. In 1631 a small church was consecrated. In 1645, at the behest of Emperor Ferdinand III., Servites came to Langegg, and soon they began the task of erecting a monastery. The west wing of the monastery was built in 1654, followed by the north wing in 1682 and the south wing in 1733. In 1773 master builder Michael Ehmann completed the new church. Its picturesque interior is mainly the work of Josef Adam Mölk (1714-1794).
During the plague outbreaks of 1630, 1634, 1646-50, 1679-81 and 1714, "Mary, Salvation of the Sick" became one of the most important plague pilgrimage sites in the country. Pilgrimages also flourished in the 18th century. In 1739, at the height of popularity, 39,000 pilgrims participated.
Under Emperor Joseph II., Langegg, together with villages belonging to the parishes of Arnsdorf and Gansbach, became an independent friars' parish in 1783 and was conferred to the Servites. Pilgrimage was banned, only to soon be resurrected. In 1913 more than 12,000 received communion, including 90 closed processions.
In 1974 the Servites left Maria Langegg and conferred the parish to the diocese St.Pölten. The monastery building served as a homemakers' school of the Institute of the Blessed Virgin Mary ("English Maidens") between 1980 and 1990, then as the diocese' institute of education and from 1993 as the residence of the Community of the Beatitudes.