The executive council of the ASTI has voted in favour of balloting its 17,000 members on industrial action.
The union, which represents secondary school teachers, voted today on the action, which could include striking, over the unequal pay of those who entered the profession since 2010.
The ASTI said that since it took industrial action over the same issue in 2016, there has been "some improvement" in new teachers' pay.
However, it said that unequal pay still remains which led to its passing a motion today "that the ASTI ballot for industrial action up to and including strike action for equal pay, to be taken in conjunction with one or both of the other teacher unions".
ASTI President Deirdre Mac Donald said: “It is unthinkable that in 2020 some teachers have inferior pay arrangements even though they are doing the same work as their colleagues in the next classroom.
"In taking industrial action in 2016, ASTI members lost pay and were further penalised under FEMPI legislation, and are still suffering the consequences.
She said that, despite this, the action "put unequal pay firmly on the agenda".
She concluded: "In addition, the ASTI’s actions led to some gains for lower-paid teachers, but full pay equality remains to be achieved and we intend to achieve it.”
