The Petrinum Grammar school celebrated its 350th Jubilee Year in 1992.

Co-operation in 1642: During the 30-year War the Franciscan Monastery and the town decide "that the local children should be educated in Latin, in etiquette and in particular the right religious belief and at not too high a cost and under the supervision of the parents" (Notitia historica Conventis Durstensis)

Final phase of the Thirty Years War. The first School Building - Westgraben	1642	The Petrinum is founded jointly by the Franciscans of Dorsten and the Town of Dorsten on the 1st November 1642. The many wars during the 17th and 18th centuries have ruined the town. The Franciscans, on their own, ensure the continuation of the school.
	1823	The "Petrinische Gymnasium" (Petrinische Grammar School), as it was clasiified in 1807, receives the status of a "Progymnasium", whose pupils leave after a total of 10 or 11 years of education (in the 10th or 11th class).
Queen Victoria, Queen of Great Britain between 1837 and 1901	1837	The last head-teacher of the Franciscan Order dies in this year.
School Building - Klosterstraße	1904	Following its expansion into a Grammar School providing a complete education in the humanities, the Petrinum says farewell to its first A'level students (1903/04). In the following year, the Grammar School has 295 pupils, taught by 16 teachers.
Palestine gains a constitution under English protectorate.	1920	The town makes an agreement with the neighbouring municipalities of Hervest and Holsterhausen to add a secondary modern school (Realschule) to the Petrinum.
Teacher Training College - Bochumer Straße	1923	The Belgians and the French occupy the town and set-up their headquarters in the school buildings. The Petrinum has to move into the former teacher training college, Bochumer Straße.
Japan leaves the League of Nations.	1933 - 1945	During the NS-Era, the school continues as a Grammar School teaching classics.
Initially, following the re-opening of the school, the lessons can only partially be taught because not all of the teachers have returned from the war, yet.	1946	Initially, following the re-opening of the school, the lessons are reduced because still not all of the teachers have returned from the war.
Building Alterations - Bochumer Straße	1963	The school community celebrates the erection of the new building and the alterations to the old school building, Bochumer Straße.
The Schmidt Government fails in a vote of no-confidence. New Building - Maria Lindenhof	1982	In this year, the Petrinum starts up lessons in its new location in "Maria Lindnhof".
	2003	The building extension is completed, thereby considerably improving the classroom situation.