Local government and school support workers in England, Wales and Northern Ireland are to mount a second day of strike action later this year.
The walkout, scheduled for September 30, follows widespread disruption on July 10 to councils, schools and fire services when more than a million public sector workers mounted strike action.
Trade union Unison urged the Local Government Association to take part in further talks to resolve a pay dispute.
It said 90% of local government and school support workers are receiving a 1% pay rise after three years of pay freezes and below-inflation pay rises.
Unison head of local government Heather Wakefield said: " The strike on July 10 sent a strong message to the employers that local government and school support workers are fed up and angry with being exploited.
"It is a disgrace that so many workers and their families are forced to live on poverty pay.
"There was widespread public support for our members, the majority of whom are low-paid and part-time women workers whose goodwill has been taken for granted for too long."
Schools across England and Wales closed on July 10 and there was disruption to council services, museums and galleries, the fire service, courts, driving test centres, libraries and jobcentres.
In 66 local authorities in England, almost 3,000 schools, nurseries and colleges reported that they had been affected by the walkout, with some forced to close entirely.
Many of these figures did not include academies, which are not under local council control.
Caretakers, teaching assistants and other school staff took part in the action, alongside teachers.