A grammar school was established in 1857, before the Town of Collingwood was incorporated in 1858. As there were no public buildings and no schoolhouse, the grammar school was started in 1857 in the International Hotel, on the south-east corner of Huronatario and Simcoe Streets, where the Bank of Montreal is now. Students had to pay to attend and the Headmaster for the first three years was Reverend John Langtry, whose salary was $100 a year. The school moved around a lot in the early years, from the True Blue House, now the site of the Gayety Theatre, to a frame house on the east side of Pine Street, and ten to Rock Court, Rev. Langtry's home on St. Vincent Street. The school was then given quarters in part of the town hall, which was also occupied by the Orange Hall and the fire hall. It stood at the north entrance to the railway grounds, near the present museum. The building was moved across the street in 1873 where it now stands as a residence at 38 S. Paul Street.

In 1874 a brick school was built on Hume Street, where its high tower made it a Collingwood landmark. In 1879, an addition was built, and "Collingwood High School" became a collegiate, the first in Simcoe County. It became one of the chief educational institutions in Ontario, thanks to Mr. Williams, the principal, and his staff. Students from all over Ontario came to Collingwood to attend Collingwood CI, and they had to pay for their education. From a total student population of two hundred and ninety five in 1879, seventy four were from Collingwood, ninety were from other parts of Simcoe County, and one hundred and thirty one were from other areas of Ontario. In 1894, the annual fees were $7.50 for local residents, $10.00 for Simcoe County Residents and $15.00 for those from outside the county. Collingwood CI was a model for many schools, patterned on programs developed by Mr. Williams, who left the school in 1901. While rehearsing for the Christmas concert on December 21, 1923, students sang about the school burning down. Their practice was interrupted by fire truck racing down the street and the discovery that the school was, in fact, on fire. The school was destroyed in the fire. The opening verse of CCI's School Song reflects the construction of the new school.

A new school was built on the site of the old one, on the northeast corner of Hurontario Street and Hume Street. While the new school was being built, classes were held on the second and third floors of a vacant store at 109 Hurontario Street. Monthly fire drills were started in April 1924. The new Collingwood CI opened on January 6, 1926, with 11 teachers and 300 students. The new school contained an auditorium and a gymnasium.

On January 1, 1951 a new school board was established, incorporating Nottawasaga Township (now Clearview Township) and parts of its neighbours. Students from Creemore, Stayner, Wasaga Beach and surrounding communities were bused to Collingwood District Collegiate Institute (CDCI). The student population of CDCI continued to grow. A new school was built, at a cost of over one million dollars, on an 11 acre site at the southwest corner of Hurontario and Cameron Streets. Part of the school was built on a marshy swamp, and in later years there were problems, such as when the gym floor bulged, and digging into the high water table when an elevator was installed.

On March 29, 1954, the entire student population of 710 students of Collingwood Collegiate watched as the flag was taken down in front of the old building. The Cadet Band led staff and students up Hurontario Street to the new school, where the flag was raised. The school was officially opened on April 30, 1954. The new school included 25 classrooms, a double gym, a rifle range and a cafeteria with a seating capacity of 175 people. The grounds provided 2 ball diamonds, a football field and track, agricultural plots and room for expansion.

In September of 1963, a vocational wing was added, providing shops for training in such area as auto mechanics, carpentry and electronics. The cafeteria was also expanded at this time. In the 1970's C.C.I expanded again. Another gymnasium, a modern library and a science wing, were added to the southern end of the school. A fully equipped business wing graced the eastern section.

1971 To 1996

In 1971, the credit system was introduced to CCI. Students accumulate credits towards a graduation diploma, and no longer fail a year when they are unsuccessful in a course. This new system led to the development of many new courses that rivalled the traditional subjects. to ensure that students received a balanced education, compulsory subjects were introduced.

The semester system brought further change to the staff and students of CCI in 1975, as students attended four 76 minute classes each day. Semester one starts in September and goes to the end of January and semester two starts in February and ends in June. Students are able to take four subjects each semester. OAC (Ontario Academic Courses) replaced grade 13. For a grade 12 diploma, students need 30 credits and 6 OAC's to be considered for University Education.

Music replaced the bells that regulated classroom times. Straight rows of desks were replaced by tables that allow for group interaction. Activities and independent studies began to place the emphasis more on a student centred rather than a teacher centred approach to learning.

By 1990, CCI could boast of a number of unique programs such as Minn-a-kee and Tionnontante, our Outdoor Education programs, and World Class, a global studies program. Collingwood Collegiate is home to sports teams, which over the years have won many championships.

In 2001, Collingwood Collegiate Institute, is home to over a 1400 students and 80 teachers, many of whom participate in the many sports, clubs and organizations offered at Collingwood CI in addition to their regular classes.