Over 450 Southampton council workers in social work were set to strike on Wednesday of this week.
The Unison and Unite union members include social workers, occupational therapists, contact supervisors and others, working with children as well as adults.
Their action was set to kick off a week of strikes by 50 workers in the adoption, fostering and residential child care sections.
And a further one-day strike across social work is planned for later in August.
They are the latest group to join the fight across the council against bosses forcing through 5 percent pay cuts.
Council workers have taken nine weeks of rolling action against the cuts, with groups from refuse workers to bridge toll collectors walking out.
Unison branch secretary Mike Tucker said, “The extended strike action by social workers demonstrates the depth of the anger over the council’s actions.
“The industrial action will spread unless the council negotiates a fair settlement with its workforce.”
The bosses tried to “divide and rule” social workers by offering some sections a payment of £1,400 to offset the pay cut.
But the union members have stood firm, rejecting this offer at a mass meeting. The unions say the payments are “part of the problem, not a solution”.
The strikers will include workers offered the extra money and those not eligible for it.
They will rally together on Wednesday, alongside other sections of council workers striking that day.
Join the picket lines from 7.30am this Wednesday
3 August: Marland House, Oakhill House, Herbert Collins House, Thomas Lewis House, Cannon Street and College Keep. Strike rally: 11am, Guildhall Square, Southampton.
Send donations to Unison office, Civic Centre, Southampton, SO14 7NB (cheques payable to Unison Southampton District Branch), and Unite at TGWU 2/8 strike fund, Unity Trust Bank account no. 20185358, sort code 08-60-01.