The walkout by social workers at Kirklees Council has been organised by Unison, which has urged all members of the union at the local authority to show their support for the dispute.
Unison said the industrial action is being taken due to poor pay and a doubling of workloads for social workers over the last five years. It said conditions have resulted in high levels of stress for staff, an increase in vacancies and a reliance on agency workers. It also cited bullying as an issue.
According to the union, social workers are quitting the council and then being rehired as agency workers for more than £10,000 a year more. It claims that 10 agency social workers were recently paid £498,000 for a six-month contract.
"Members have had enough. Enough of bullying, enough of stress, enough of vacancies, enough of poor pay, enough of agency staff and enough of austerity," said Paul Holmes, Kirklees Unison branch secretary.
"You can only work under stress for so long - once it becomes a way of life, then stress illnesses soar and people who thought of themselves as strong start to ‘go under'.
"That is nothing to do with weakness and everything to do with increasing workloads and ‘no light at the end of the tunnel'.
"Our members have had enough of doing a difficult job in stressful circumstances for inadequate pay."
Children's services at Kirklees were rated "inadequate" after an Ofsted inspection last September and October, which identified concerns at more than a third of children's cases looked at.
Unison's decision to strike comes a month after it put industrial action on hold due to concerns that Leeds City Council would not agree to work in Kirklees if such action was taking place.
The union's preferred option is to see Kirklees retain control of children's services and it sees a temporary take-over by Leeds as the most realistic way to achieve that.
Unison said it now understands that the Leeds option will be put in place, whether strike action takes place or not.
"The vibes the union was getting from Leeds City Council was that they may walk away from a deal if there was strike action. I'm not getting those vibes now," said Holmes.
"All the signs within the council are that the council want the management rather than the employment to go to Leeds. It looks like the director of children's services in Leeds will run our children's services for a period."
Eleanor Brazil, who was last year appointed in Kirklees to advise government on whether alternative delivery arrangements are necessary, has submitted her findings to ministers, but a final decision was delayed by the general election.
She condemned the strike action for undermining confidence among staff and families in the work being carried out to improve the department.
"It is extremely disappointing that Unison have chosen to pursue industrial action, despite the assurances they have received from the senior leadership of the council," she said.
"Staff in children's services are working hard in difficult circumstances as we all aim to improve services and achieve the highest possible standards of support for children and families.
"This action does not help staff and families to develop confidence in the steps that are being taken to achieve positive changes."
Erin Hill, lead member for children's services at Kirklees Council, said: "Part of the frustration I feel personally is that we have done all we can to include and understand Unison's position throughout the improvement process.
"It is not for me to say whether this is the best way of representing their members, but I feel certain that the voice of the children we represent is lost when this kind of action is taken.
"The vast majority of staff I speak to are incredibly committed to protecting the most vulnerable children in Kirklees, which is our top priority."