Thousands of staff in further education colleges in England, including lecturers, librarians and cleaners, are going on strike today in a row over pay.
Members of the University and College Union (UCU) and Unison are taking industrial action in protest at plans for a pay freeze.
The unions claim some staff have suffered a real-terms pay cut of up to 17% after several years of low wage rises.
Picket lines will be set up outside hundreds of colleges, while rallies will be held in London and Manchester.
Unison general secretary Dave Prentis said: "Some colleges have promised their employees a pay rise, but the vast majority are determined not to budge from the zero per cent recommended.
"We urge the Association of Colleges to follow the example of those more enlightened colleges who want to come back to the table to try to resolve this dispute.
"The real villains in this dispute are government ministers, whose funding cuts over several years have left colleges in dire financial straits.
"After years of pay freezes and real-terms pay cuts, staff have been left with no choice but to take action to win a fair deal."
UCU general secretary Sally Hunt said: "A pay freeze is an insult to the commitment and enthusiasm of staff working in further education, and fails to address the real-terms pay cut they have suffered in recent years.
"Strike action is always a last resort but our members are clear that the Association of Colleges needs to return to the table with an appropriate pay offer in order to resolve this dispute."
Members of both unions backed industrial action in ballots.