Ten of thousands of people across Northern Ireland are set to stop work in protest at terrorism.
The move comes following the sectarian murder of Catholic postal worker Daniel McColgan and death threats against his colleagues and teachers.
Businesses, public services and schools are expected to come to a standstill as workers attend protest rallies organised by the trades unions.
Tom Gillen, deputy assistant general secretary of the Congress of Trade Unions, says it is important to make a stand against violence and intimidation.
He said: "The day of action is a significant and important opportunity for the whole community in Northern Ireland to unite against terrorism and sectarianism."
He welcomed the co-operation of government, business and the churches in making the stand, saying: "We must all show that we want an end to murder, intimidation and threat."
Noon rallies are being held at six venues across the province - with the largest taking place outside Belfast City Hall.
Protests are also taking place in Derry, Enniskillen, Omagh, the border town of Newry and Cookstown, Co Tyrone.
Public transport will be heavily hit. Train services will shut down for two hours and bus services will be heavily cut. Banks have warned customers to expect a restricted service.
Teachers at the heart of the protest and many schools are expected to close for the day, while others will send their pupils home early.