Some teachers at a Belfast primary school will begin a three-day strike on Tuesday due to a continuing dispute.
Members of the NASUWT union in St Patrick's Primary School previously took six days of industrial action last November.
The NUSUWT said the failure of the school to address members' concerns was responsible for further action.
The principal said the school would not close as the majority of its teachers would be at work.
About one third of the school's 27 teachers are NASUWT members.
Their action is planned for Tuesday 2 April to Thursday 4 April.
"This action is as a result of the continuing failure of the employer to respond appropriately to the deep concerns of teachers at the school about the culture in which they are expected to work, which is having a detrimental impact on their working conditions, their health and wellbeing," the union said.
The NASUWT general secretary, Chris Keates, said sufficient progress had not been made in addressing those concerns.
"Following the previous strike action in November, the NASUWT engaged positively and constructively with the employer," she said.
"However, all these months later the teachers at the school have yet to see an improvement in their working environment.
"They need tangible changes now, not months down the line."
St Patrick's principal Margaret Neeson told BBC News NI: "The education and wellbeing of our pupils is our priority.
"The school will remain open as we are focused on that."
In a statement to BBC News NI, the Council for Catholic Maintained Schools encouraged the NASUWT to continue to engage in attempts to resolve the dispute and said the outstanding issues would not be resolved through industrial action.