Members of the Teachers' Union of Ireland (TUI) have voted overwhelmingly in favour of industrial action, up to and including strike action.
It is part of a campaign to end pay discrimination.
Members have voted by a margin of 92% to 8% to endorse the union's mandate for industrial action.
TUI says it has "once again" highlighted the damage inflicted on the education system by pay discrimination.
The union says it is frustrated by the "Government's inaction on this critical issue".
It is calling for "real engagement" from Education Minister Joe McHugh.
"The ballot result makes clear that members are united in solidarity with new and recent entrants and are prepared to take industrial action should the process of pay equalisation not be completed in the near future," it adds.
TUI President Seamus Lahart says: "Yet again this year, a new cohort of teachers has entered the profession being paid at a lesser rate than their longer-serving colleagues for carrying out the same work.
"Progress has been made in this campaign, but our members have run out of patience with the Government's failure or unwillingness to complete the process of pay equalisation."
"This ballot result makes clear that TUI members, regardless of career stage, are united on this issue and are willing to take action, up to and including strike action, unless further progress is made without delay.
"Minister McHugh should take heed of our resolve."
It says the largest differences in pay between those employed before and after January 1st 2011 still occur in the early years of employment - with new entrants to second-level teaching earning 14% less on initial appointment, and 10% less in the first 10 years than they would have before the introduction of cutbacks.