Thousands have taken to the streets of cities throughout Britain to call for higher wages for public sector workers.
The protests have been organised by the TUC under the slogan "Britain Needs a Pay Rise", and are being attended by public sector workers including teachers, nurses, civil servants and hospital workers, as well as by many from the private sector.
The main rally is being held in London, but others are being held in Glasgow and Belfast.
The demonstrators are protesting against the government's offer of a pay rise of 1% below inflation.
The TUC claims that public sector wages have fallen £50 per week in real terms since 2008.
"Our message is that after the longest and deepest pay squeeze in recorded history, it's time to end the lock-out that has kept the vast majority from sharing in the economic recovery," said Frances O'Grady, TUC general secretary.
"The average worker is £50 a week worse off than in 2007 and 5 million earn less than the living wage. Meanwhile, top directors now earn 175 times more than the average worker.
"If politicians wonder why so many feel excluded from the democratic process, they should start with bread-and-butter living standards."
Marchers in London held aloft banners and blew whistles and whistles.
They will march past the Houses of Parliament, before attending a rally in Hyde Park, where union leaders will give speeches.
Earlier this week, nurses and other NHS staff went on strike over the government's refusal to offer all NHS workers the one per cent pay rise.
Over coming weeks, hospital radiographers and prison officers will take part in strikes.