The union said it will stage a massive demonstration in Toronto if Premier Dalton McGuinty's government tries to legislate a wage freeze for teachers.
The last time they took the same action was in 1997, when Mike Harris was premier.
McGuinty has asked teachers to accept a "real two-year wage freeze" as part of recent austerity measures.
Ontario teachers start at $41,766 to $44,292, and can make up to $92,813 in elementary schools and $94,942 in secondary schools, depending on years of service and education.
The government wants to freeze the grid so no one gets a raise because of seniority or improved credentials.
The teachers' federation has called the details of the government's position "offensive."