A quarter of a million teaching assistants, dinner ladies and caretakers will hold a one-day strike later this month in protest at plans to cut pensions for those who retire early.
Unison, the largest support staff union, voted by four to one in favour of strikes after the Government refused to protect existing pensions despite agreeing to do so for teachers.
School support staff will be among more than a million local government workers in nine unions who will walk out on March 28 in what they say will be the biggest strike since 1926.
Their unions, including the GMB and TGWU, are expected to be joined by local authority members of the National Union of Teachers and the Association of Educational Psychologists.
The NUT was expected to announce the results of its own ballot as The TES went to press.
The strike, which will involve local government members of up to eight other unions, is likely be followed by action targeted at different parts of local government including schools.
The Government's proposals would prevent all 1.5 million members of the local government pension scheme, including staff in council education departments, retiring before the age of 65 on a full pension.
Although their official retirement age is already 65, support staff can take advantage of Rule 85, which allows people whose combined age and length of service equals 85 or more to retire earlier on a full pension.
Unions are pressing for that rule to be protected for existing staff. They point to an agreement reached in October which will preserve the retirement age of 60 for existing teachers and civil servants.
The changes would cost a full-time teaching assistant earning pound;15,000 almost pound;2,000-a-year from their pension if they decided to retire at 60.
Unions say many support staff already lose out because they are only paid during term time and that 73 per cent of local government pension scheme members are women whose average pension is just pound;31 per week.
Dave Prentis, general secretary of Unison, said: "After a lifetime of dedicated service to their local communities, our members deserve the pensions they have already paid for."
He said that three-quarters of the people in the local government pension scheme were women - "who did exactly what the Government told them and started paying for their retirement out of their earnings - and now because of the financial mismanagement of their employers, the rules get changed and they have to work an extra five years.
"We have been negotiating for months over this, and it is still not too late for the Government and the employers' association to sit down and talk sense."
An Office of the Deputy Prime Minister spokeswoman said the Government would continue discussion with unions.
She said: "The difference between the LGPS and the public schemes is that this is a funded scheme which is dependent on investment income. This is why it is dealt with separately."