1900  Addition of Stack Wing
1934  Addition of Librarian's office and extension to the stack wing
1956  Addition of a wing at the front and east side of the building
1991  Electrical and code renovations and the installation of an elevator
2006  Major renovation and expansion. The stack wing and 1956 wing were demolished, and new construction doubled the square footage of the library. Architect: Lerner, Ladd, and Bartel. Contractor: Delulis Brothers. The project was made possible through a grant from the Board of Library commissioners, Town of Watertown funds and the generosity of the community.