At the beginning of the last century the Bishop of Ljubljana, Anton Bonaventura Jeglič, realised the importance of establishing a gymnasium and institution where students would be educated as intellectuals as well as nationally-conscious Slovenes and good Christians. Part of the necessary resources were raised by the Bishop with the help of several priests, but above all the Institution was built with contributions of the common Slovene faithful.
In July 1901 Bishop Jeglič blessed the foundation stone. The first two thirds of the institution were already finished by 1905; the last third (the left wing) was completed in 1910. After many years of effort, St. Stanislav's Institution was the first Slovene gymnasium. On the front of the building the founder inscribed: To Christ – the Saviour of the World.
The gymnasium’s mission was the upbringing of character as well as the education of the intellect, holding to the principle that “a learned person in the realm of science can be simultaneously a nobody of character.”
In 1913 the first maturity examination (comprehensive exit exams or “A levels”) at the first Slovene gymnasium was a historical one – it was conducted in the Slovene language for the first time.
During the First World War there was an army hospital in the Institution and upper-class students were mobilised into the military. After the war the Institution carried on its mission under new circumstances and in a new state (Yugoslavia).
On 28th April 1941 the building was taken over by German occupying forces. The students and the staff had to vacate the building within three hours. However, the process of education more or less continued in different locations in Ljubljana. The school was officially closed on 5th June 1945 and the Institution was taken over by the Yugoslav army. In May and June 1945 the building and its surroundings were used as an assembly centre from which thousands of Slovene anti-revolutionists were taken to execution. After that the Institution served as barracks for the Yugoslav army.
In 1991, after Slovenia’s independence, the first democratically elected government returned the building to its original owner - the Archdiocese of Ljubljana. On 13th November 1992 Archbishop Dr. Alojzij Šuštar legislatively re-established St. Stanislav's Institution for education. In its realm the following constituents have been gradually set into operation: the Gymnasium, the Student Home, the Music School, the Slovene Home, the Residence Hall and the Primary School.
Before WWII the DCG educated the future Catholic Slovene intelligentsia who shaped the religious, cultural and social image of the Slovene nation during the greater part of the 20th century. On the feast day of St. Stanislav (13th November), the patron of the Institution, former and present generations of students meet, marking the occasion with Holy Mass and a solemn celebration. At the celebration the Archbishop recognises those students who displayed academic excellence.
The first director was the prelate Borut Košir, Ph.D., who deserves much credit for the reinstallation of this Slovene cultural and educational centre during his seven year tenure.
He was followed by Anton Jamnik, Ph. D., who successfully led the Institution until the celebration of its centenary. On 15th November 2005 he was appointed Auxiliary Bishop of Ljubljana by Pope Benedict XVI.
In January 2006 the Archbishop of Ljubljana, Msgr. Alojz Uran, entrusted the directorship of the Institution to Roman Globokar, Ph. D., who eagerly assumed the post.
Archbishop Alojzij Šuštar lived at the Institution from his retirement in April 1997 to his death on 29th June 2007. Through his residence and prayers he enriched the daily life of the Institution. Sister Mira Rožanc devotedly cared for him.
In 2005 the Institution celebrated its centenary. The jubilee was marked by several important occasions.