In 1875, a one room school was built for the English population of St. Lambert. Over the next 20 years, (1895) the school, often referred to as “The Model School” had an enrolment of one hundred students with five teachers. The increase of enrolment was mainly due to the construction of the “Montreal and Southern Counties Railway.” St. Lambert was a very attractive county in which to settle and raise a family because Montreal was easily accessible and growing.
In 1896 St. Lambert Elementary was built. The land was sold to the “School Commissioners of St. Lambert for $3,000 by Mr. Noël Mercille. Mr. Mercille had been a municipal councillor for 19 years. During those years, he served as mayor of the “St. Lambert Village” and pushed for the development of St. Lambert. The residents not only had a $7,000 new school, but also had the name changed from the “Model School” to “St. Lambert Academy”.
In 1912, the school was extended in order to accommodate the students from Chambly County. Over the next few years, the school was faced with a severe shortage of space. The school rented space from the “St. Lambert Lumber Company” at $ 600. per month and the Kindergarten classes were held at a teacher's house. (Mr. C.J. Davis). In 1921 – 24, two new wings were added to the school, this included 10 extra classrooms, a gymnasium\auditorium costing 225 000$. The school's name was changed from “St. Lambert Academy” to “St. Lambert High School”. The school enrolment was up again to 694 students in 20 classrooms.
Janet Brown, a student who attended St. Lambert Elementary School remembers the school, “It was an old school with beautifully polished old wood floors…. that sometimes creaked. There was a nice old staircase with a banister inside the front door. The science lab for biology and chemistry was in the low-ceiling basement. The well liked janitor and his wife. Mr. & Mrs. Sylvester lived in the basement apartment provided for them and this meant there was very little vandalism or break-ins at the school”… In the 1940's space again became an issue. This was largely because in 1944, the Central School Board Act was passed, putting St. Lambert School Board under the Chambly County School Board. This meant that St. Lambert High School accepted students from other Counties. So in 1947 the St. Lambert School Board purchased the”Colour Research Building”, on Green Street. This building was known as the “Annex”, it housed “6 classrooms, with a capacity of 200 students”. Today that building is the “St. Lambert Library.” St. Lambert Elementary and St. Lambert High School shared the same building.
Then in 1949, the High School was renamed "Chambly County High School" and in the Autumn of 1954 the school was relocated to the new building at 675 Green Street.
At the end of the 1999 school year the school changed it's name once again to "Chambly Academy" when Chambly County High School and Penfield Academy were amalgamated into one school.
Following the sale of land behind the school, extensive additions and renovations were made and were officially opened on November 5, 2009. These included a complete renovation of all interior aspects of the school, a new wing housing a state of the art gymnasium, a new library and a new student resource center.
On January 20, 2015 the Riverside School Board Council of Commissioners approved a request from the Chambly Academy Governing Board to change the school’s name to "Saint-Lambert International High School". The new name came into effect on July 1, 2015. This change was made to better reflect the location and mission of the school and to return to our roots described above which stretch all the way back to 1875!