More than 700 delegates have gathered in Killarney for the Irish National Teachers' Organisation Annual Congress.
Issues to be debated include budget cuts to teacher ratios in small schools.
Secondary school teacher unions, the ASTI and the TUI, begin their conferences in Cork and Wexford tomorrow morning.
The INTO conference began with an address from its president.
Addressing fears for the future of the Croke Park agreement, Noreen Flynn told delegates that teachers were keeping their side and they expected the Government to do the same.
Tomorrow the union will debate a motion calling for a ballot for industrial action if that does not happen.
Ms Flynn also warned against further reductions in the pay of new entrants to the profession.
On small schools she said the budget proposals that cut teacher numbers had caused fear and anxiety in rural, gaeltacht and island communities.
She said the cuts were seen as an attack on the existence of these communities.