1952 A second storey was added to the Junior School and opened during the School’s Jubilee celebrations.

1953 The Parents’ and Friends’ Hall was built near Merritt House.

1956 The Art Building was completed and used also as a Middle School.

1958 A number of schools left the AGSV to join the Associated Public Schools of Victoria (APS). Trinity won the AGSV Athletics Premiership, the first of twelve out of thirteen years in a row.

1959 Mr. John Leppitt was appointed Headmaster. The Robertson Science and Administration Building was opened.

1961 The Junior School Building (now the Watson Building) was extended to provide art and music facilities. The tennis courts at the corner of Wellington and Charles Streets were removed and the Junior School Oval (now the Taffs Oval) was formed.

1962 The School's population reached 812 students.

1963 Trinity won four out of five AGSV Premierships, a feat which was achieved again in 1964.

1964 The Robertson Building was extended along Wellington Street.

1968 The four storey Shann Building was constructed between Arnold Hall and the Robertson Building. Construction of the Cornell Gymnasium commenced.

1970 Changes were made to expand the P&F Hall and a second floor was added to the Administration Building.

1973 The Leppitt Outdoor Education Centre was established at Lake Eppalock.

1975 The Boarding House was closed.

1976 Roberts House was converted for the Preparatory to Year 3 classes. The Tonge Building was built.

1979 Mr. Don Marles was appointed Headmaster.

1980 The 25m Swimming Pool was constructed.

1982 The Science Laboratories were reconstructed and named the Bright Laboratories. Merritt House was converted into the Music School. The School's population reached 998 students.

1983 The Bulleen Playing Fields were opened.

1984 The P&F Hall was further redeveloped and the Batson Quadrangle was paved.

1986 Reconstruction of Arnold Hall was completed and an area in front was paved.

1988 The Administration was redeveloped and included construction of a Roof Garden and was renamed the Hindley Building.

1989 Further renovation of the P&F Hall took place, and the Poynter Building was completed.

1990 The Tuckshop on the western side of Charles Street was replaced by the Cafeteria on the ground floor of the Shann Building. Trinity won their first AGSV Hockey Premiership.

1992 The Watson Building was extensively renovated to provide Junior School classrooms and offices. The Chapel of the Holy Trinity was built.

1993 Mr Peter Crawley was appointed Headmaster. Middle School classrooms in the Watson Building were reconstructed.

1993 Notebook computers were introduced to the curriculum for students in Years 5, 7 and 9.

1995 Trinity won the AGSV Athletics and Cricket premierships.

1996 The School purchased the former Kew Municipal Offices. Trinity won the AGSV Basketball Premiership, following this with equal success in 2000 and 2001.

1997 The Cohen Centre was opened at Bulleen.

1998 The Centre for the Arts (former Kew Municipal Offices) was opened.

1999 Mr Richard Tudor was appointed Headmaster. The Early Learning Centre was opened. The playing fields at Bulleen were renamed the Marles Playing Fields.