Delegates in Bournemouth voted for "rolling industrial action up to and including strike action" if demands for an immediate pay rise of 10% or at least £2,000 for all teachers and a £3,000 rise in the London allowance were not met.
The union's general secretary, Doug McAvoy, is prepared to repeat strike action in London if necessary but wanted their demands on the allowance to be limited to a £1,500 rise, and he is opposed to a generalised strike over pay.
Conference has also voted to strike if pay and conditions are threatened by privatisation, and if professional development courses take place outside the school day, to refuse to cover for more than one day for absent colleagues, and to boycott national tests at seven, 11 and 14.
Mr McAvoy and the executive are opposed to all of those - although they did win unanimous backing for enforcing a 35 hour week in the autumn with the other main classroom unions if the chancellor's spending review and the forthcoming report on teachers' pay and conditions failed to reap sufficient benefits.
Despite an unusually long standing ovation for Mr McAvoy after his closing speech to conference yesterday, the leadership has been bruised. Former president Tony Brockman described the vote over pay yesterday as a "spectacular own goal".
But the union's left believes he and the executive are using appeals for unity with other classroom associations to try to moderate NUT demands. "The executive brought no unity motion on salaries to conference. In that situation we have to develop our own alternative," Kevin Courtney, from Camden, central London, told conference.
Once again the union has received television coverage for noisy protests at outside speeches - by Estelle Morris, the education secretary, and Damian Green, the Tories' education spokesman.
Mr McAvoy defended the NUT's strike last month over the London allowance. "The vast majority of the thousands who took part weren't dinosaurs, weren't dyed in the wool militants. They are young teachers. They marched that day with a pride in their professionalism."
But he added: "Whatever cheering and jeering, whatever tirades and whistle-blowing, whatever catcalls and walkouts, at the end of this conference you have to get teachers on your side.
"The vast majority of teachers know that industrial action is a means not an end... our campaigns should be conducted in such a way that we gain and keep the support of parents."
