27th January 1867: a small school started by Miss O'Mara under the pastoral guidance of the Parish Priest, Father O'Reilly in the first Catholic Church.
1873: Father Stephen O'Donough applied for a few Sisters of Mercy to come to Warwick.
29th October 1874: Sister Magdalen Rooney, first Superior, and two other Sisters of Mercy arrive renaming the school St Mary's School working out of the Oddfellows Hall.
1876: Mother M Kevin arrived and set about building St Mary's Primary School.
1891: Foundation stone of new convent laid and blessed by Archbishop Dunne.
1893: Convent opened by Archbishop Dunne.
1905: Father Michael Potter, later Monsignor Potter, was appointed the new Parish Priest of Warwick and set about starting building plans for St Joseph's College and the Second St Mary of the Assumption Church.
1912: The Christian Brothers arrived in Warwick to work at St Joseph's College for boys in Grades 4-12. The first community of brothers were first Superior, Athanasius Kelly, along with Stanislaus McIntosh and Mark Reidy.
1912: Secondary education for girls started in primary school building by Sister Mary Vincent Donovan.
1914: Secondary School transferred to rooms in convent. Boarders annexe added; opened by Archbishop Duhig.
1942: Warwick sheltered All Hallows' boarders evacuated during World War II.
1962: Monsignor Potter Memorial School built.
1969: Assumption College built.
1974: At the end of 1974, the decision was made on financial grounds, to discontinue Years 11 and 12 at both the Convent High School and the Christian Brothers College.
1979: Plans were made to amalgamate the Convent High School and Christian Brothers College under the auspice of the Toowoomba Catholic Education system.
1979: The first lay principal of St Mary’s School was Mr Bailey Pashley.
1980: Assumption College became a co-educational Junior Secondary College following the rationalisation of the school system in Warwick. The boys from St Joseph’s Christian Brothers College came to Assumption College as fulltime students.
1993: St Mary's Pre-School began and in 2007 Prep replaced the Pre-School.
2000-01: Assumption College introduced Year 11 and in 2001 graduated its first Year 12 class in twenty-six years.
2013: St Mary’s Kindergarten commenced with the Director, Mrs Marie Sullivan under Brisbane Centacare. In 2020, the Toowoomba Catholic Schools Office took over the governance of the Kindergarten.
2019: St Mary’s Outside of School Hours Care began under the direction of Mrs Stephanie Shelley.
2022: The Upper and Lower Campuses of St Mary's combine into one campus at 173 Palmerin Street.
In 2020: Staff, in consultation with students, have written the current school prayer. The intention was to remember where we have come from and unite us in what is important at St Mary’s – ‘The St Mary’s Way to RISE UP'.